Muscle blood flow during forearm exercise in patients with severe heart failure

Muscle fatigue is a prominent symptom in patients with chronic heart failure (CHF). To determine whether it results from an intrinsic abnormality of vasodilating capacity of the vasculature in exercising muscle, we studied local forearm blood flow (FBF) during exercise in 13 patients with severe CHF and in eight normal untrained subjects of similar age. Intermittent forearm static exercise was performed by squeezing a hand dynamometer for 5 seconds, three times per minute, for 5 minutes at 15%, 30%, and 45% of maximum voluntary contraction. FBF was measured by mercury-in-rubber strain gauge venous plethysmography at baseline before exercise and during the last 3 minutes of each exercise state. Exercise was repeated after 24 hours of intravenous administration of milrinone in the patients with CHF. FBF increased with forearm exercise in a reproducible manner during 24 hours in the normal subjects: rest, 2.54 +/- 0.23 (0 hours), 2.90 +/- 0.23, (24 hours); 15%, 7.25 +/- 0.92, 5.85 +/- 0.56; 30%, 9.20 +/- 1.08, 10.05 +/- 0.85; 45%, 14.62 +/- 1.64, 13.85 +/- 1.09 ml/100 ml/min; p = NS, 0 versus 24 hours. In patients with CHF, FBF was reduced at baseline compared with normal subjects (1.70 +/- 0.15 ml/100 ml/min, p less than 0.05), but no significant differences from normal subjects were observed during exercise (15%, 5.04 +/- 0.65; 30%, 7.64 +/- 0.99; 45%, 12.56 +/- 1.20 ml/100 ml/min). Peak exercise blood flow was correlated negatively with central venous pressure (r = -0.65, p less than 0.05) and positively with right ventricular ejection fraction (r = 0.59, p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

慢性心力衰竭患者耐量运动训练后体内神经激素的变化

目的　研究耐量运动训练能否对慢性心力衰竭 (CHF)患者血浆中精氨酸血管加压素 (AVP) ,心钠素 (ANP) ,血管紧张素Ⅱ (AngⅡ )和醛固酮 (Aldo)水平有影响 ,延缓病程进展。方法　 12例CHF患者 (冠心病 ,心功能为Ⅱ～Ⅲ级 ,NYHA)隔天在监护下进行耐量运动训练 ,为期 12 0d。在进行耐量运动训练之前和之后 ,采用放射免疫法检测每一患者血浆中在静息状态下和极量平板运动后上述神经激素的水平。结果　经 12 0d的耐量运动训练后 ,静息状态下上述血浆神经激素水平较耐量运动训练前显著降低 (P <0 .0 5 ) ,但极量平板运动后与耐量运动训练前比较则差异无显著性意义 (P >0 .0 5 )。结论　耐量运动训练可降低CHF患者在静息状态下血浆AVP、ANP、AngⅡ和Aldo的水平 ,因此 ,可能有益于延缓CHF患者病程进展。     

Cytokines and heart rate variability in patients with chronic heart failure

INTRODUCTION: Heart rate variability (HRV) analysis is a non-invasive method of assessment of the autonomic nervous system's effects on heart function. In chronic heart failure (CHF), decreased HRV correlates with the progression of the disease. It is also known that in CHF increased levels of proinflammatory cytokines are present. Because these molecules are believed to influence the nervous system at both the central and peripheral levels, their potential role in HRV reduction in the course of CHF has been proposed. AIM: The study was designed to verify potential relations between cytokines and HRV parameters in CHF patients. The concept of the study was driven by the recognition of controversies in this field and the paucity of published reports. METHODS: Forty-four patients with CHF and stable NYHA class I-IV symptoms and 15 healthy controls were enrolled in the study. Time-domain HRV analysis was performed based on of 24-hour Holter ECG monitoring. Plasma concentrations of soluble TNFalpha receptors sTNF-RI and sTNF-RII and interleukin 6 (IL-6) were measured using commercially available ELISA kits (Quantikine, RD Systems). RESULTS: In patients with CHF, HRV indices included in the analysis were significantly decreased, and the levels of cytokines increased in comparison with the control group. In the whole study population, both in the CHF patients and the control group, significant negative correlations were observed between sTNF-RI level and long-term HRV indices such as SDNN (r=-0.44; p=0.0006), SDANN (r=-0.44; p=0.0005) and short-time index SDNNI (r=-0.37; p=0.004). Similar negative correlations were found between sTNF-RII level and SDNN (r=-0.35; p=0.007), SDANN (r=-0.34; p=0.01), and SDNNI (r=-0.31; p=0.02), as well as between IL-6 level and SDNN (r=-0.41; p=0.001), SDANN (r=-0.44; p=0.0005) and SDNNI (r=-0.34; p=0.009). CONCLUSIONS: Significant negative correlations between TNF-alpha soluble receptors sTNF-RI, sTNF-RII and IL-6 levels and time-domain HRV parameters were observed in the study. Because the results of investigations conducted so far do not elucidate the cause-effect relationship, further studies are needed to clarify the mechanisms of HRV depression in CHF and the role of cytokines in this severe clinical condition.     

Exercise training improves heart rate variability in older patients with heart failure: a randomized, controlled, single-blinded trial

Reduced heart rate variability (HRV) in older patients with heart failure (HF) is common and indicates poor prognosis. Exercise training (ET) has been shown to improve HRV in younger patients with HF. However, the effect of ET on HRV in older patients with HF is not known. Sixty-six participants (36% men), aged 69±5 years, with HF and both preserved ejection fraction (HFPEF) and reduced ejection fraction (HFREF), were randomly assigned to 16 weeks of supervised ET (ET group) vs attention-control (AC group). Two HRV parameters (the standard deviation of all normal RR intervals [SDNN] and the root mean square of successive differences in normal RR intervals [RMSSD]) were measured at baseline and after completion of the study. When compared with the AC group, the ET group had a significantly greater increase in both SDNN (15.46±5.02 ms in ET vs 2.37±2.13 ms in AC, P=.016) and RMSSD (17.53±7.83 ms in ET vs 1.69±2.63 ms in AC, P=.003). This increase was seen in both sexes and HF categories. ET improved HRV in older patients with both HFREF and HFPEF.     

Combined endurance/resistance training reduces NT-proBNP levels in patients with chronic heart failure.

AIMS: This study was designed to evaluate the effects of combined endurance/resistance training on NT-proBNP levels in patients with chronic heart failure (CHF). The safety of resistive weight training for patients with CHF is questioned. Possible detrimental effects include an increase in ventricular diastolic pressure and secondary unfavourable remodelling. Circulating levels of the N-terminal fragment of brain natriuretic peptide (NT-proBNP) reflect left ventricular diastolic wall stress and are strongly related to mortality and treatment success in CHF. METHODS AND RESULTS: In this study, 27 consecutive patients with stable CHF and left ventricular ejection fraction (LVEF) <35% were enrolled in a 4 months non-randomized combined endurance/resistance training programme. Blood sampling for measurement of NT-proBNP, functional assessment, cardiopulmonary exercise testing, echocardiography and radionuclide angiography were performed at entry and after 4 months. After 4 months, exercise training caused a significant reduction in circulating concentrations of NT-proBNP (2124+/-397 pg/ml before, 1635+/-304 pg/ml after training, p=0.046, interaction), whereas no changes were observed in an untrained heart failure control group. NYHA functional class (p=0.02, interaction), maximal (peak VO2: p=0.035, interaction; maximal workload: p<0.00001, interaction) and submaximal (workload at anaerobic threshold: p=0.001, interaction; rate-pressure product at anaerobic threshold: p=0.001, interaction) exercise parameters as well as work efficiency (Wattmax/VO2peak: p=0.0001, interaction) were significantly improved. In addition, a decrease in left ventricular end-systolic diameter was observed in the trained heart failure group (p=0.016). CONCLUSION: Four months of combined endurance/resistance training significantly reduced circulating levels of NT-proBNP in patients with CHF, without evidence of adverse remodelling. Exercise training might offer additional non-pharmacological modulation of the activated neurohormonal pathways in the setting of CHF.     

慢性心力衰竭患者的心率变异性分析

目的 探讨慢性心力衰竭患者心率变异性的变化。方法 观察76例心力衰竭患者（观察组）和24例健康人（对照组）的心率变异性时域指标,比较两组各指标及与心功能程度NYHA分级、原发病和心力衰竭类型的关系。结果 观察组较对照组SDNN、SDANN显著降低（P均〈0.05、〈0.01）。心功能Ⅳ级者较Ⅱ、Ⅲ级SDNN、SDANN显著降低（P〈0.05、〈0.01）。右侧心力衰竭者较对照组SDNN、SDANN显著降低（P均〈0.01）;全心心力衰竭者较对照组和单侧心力衰竭SDNN、SDANN均显著降低（P〈0.01、〈0.05）。各种病因者较对照组SDANN均显著降低（P〈0.05、0.01）,但各种病因者差异无显著性意义（P〉0.05）结论 慢性心力衰竭患者HRV部分指标变化可作为判定慢性心力衰竭严重程度的参考指标;各项指标变化可能与原发病无关,但部分似与心力衰竭类型有关。     

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.     

步行训练对老年慢性心力衰竭患者心脏功能康复的影响

目的:观察步行训练方式对老年慢性心力衰竭患者心功能康复的效果和安全性。方法:295例Ⅱ～Ⅲ级慢性心功能不全的老年患者随机被分为康复组(152例)和对照组(143例),康复组在药物治疗基础上进行步行训练,对照组只进行药物治疗。经过6个月的随访,对比两组治疗前、后的血压、静息心率、6min步行距离、心脏超声的左室射血分数(LVEF)和左室舒张末期内径(LVEDd)等的变化情况。结果:运动训练前不同组间一般情况、血压、静息心率、6min步行距离和左室功能无明显差异(P0.05);运动训练6个月后各组死亡情况没有差别;步行运动训练组总再次住院率(20.4%∶33.6%)和因心血管疾病再次住院率(11.8%∶22.8%)明显低于对照组(P均0.05);与运动训练前及对照组治疗后比较,康复组治疗后静息心率明显下降[(72.1±15.7)次/min,(74.3±16.8)次/min∶(66.8±12.4)次/min],6min步行距离[(284.9±104.7)m,(296.1±134.5)m∶(328.6±124.2)m]和LVEF[(33.4±9.7)%,(30.4±9.6)%∶(35.9±10.9)%]均明显增加(P均0.01);血压和LVEDd无明显变化(P0.05)。结论:一定强度的步行训练对老年慢性充血性心力衰竭患者心脏功能的康复是安全和有效的。     

Circadian pattern of heart rate variability in chronic heart failure patients Effects of physical training

The effect of physical training on the circadian pattern ofheart rate variability (recorded over 24 h in relation to bothtime and frequency) was assessed in 12 chronic heart failurepatients randomized, in a cross-over design, to 8 weeks trainingor detraining, and compared with 12 age-matched normals. Trainingimproved heart rate variability indices: all R-R interval 5min standard deviations increased by 17.6%, the root mean squareof the differences of successive R-R intervals by 34.9%, thepercentage difference between adjacent normal RR intervals>50ms by 112.5%, total power by 58.3%, high frequency by 128.5%and low frequency by 65.0%. Compared with controls, circadianvariations in autonomic parameters were maintained in chronicheart failure. Training-induced changes were observed at differenttime intervals throughout the day: the highest values were at0100 h-0700 h (detraining: low frequency 361±83 ms²,high frequency 126±47 ms²; training: low frequency 535±202ms², high frequency 227±115 ms², P<0.01) and the lowestat 1300 h-1900 h (detraining: low frequency 91±23 ms²,high frequency 39±14 ms²; training: low frequency 154±42ms², high frequency 133±67 ms², P<0.05). In chronicheart failure, training maintains and improves circadian variationsin heart rate variability measures.     

Supervised exercise training improves aerobic capacity and muscle strength in older women with heart failure

BACKGROUND: The effect that supervised or unsupervised exercise training has on aerobic capacity (peak oxygen consumption [VO2peak]), muscle strength and quality of life in older women with heart failure remains unknown. OBJECTIVE: To examine the effect of six months (three months supervised followed by three months unsupervised) of aerobic training (AT) or combined aerobic and strength training (CAST) on VO2peak, muscle strength and quality of life in older women with heart failure. METHODS: Twenty older women (mean age +/- SD, 72+/-8 years) with clinically stable heart failure were randomly assigned to AT (n=10) or CAST (n=10). Supervised AT was performed two days per week at 60% to 70% heart rate reserve, whereas unsupervised training was performed two days per week at a rate of perceived exertion of 12 to 14 on the Borg scale. The CAST group also performed one to two sets of low-to-moderate intensity strength training two days per week. RESULTS: Supervised AT or CAST resulted in an increase in VO2peak (12%; P<0.05) and leg press strength (13%; P<0.05) that returned to baseline after unsupervised training. Vertical row strength was greater (+23%; P<0.05) after supervised CAST and remained unchanged after supervised or unsupervised AT. Supervised or unsupervised exercise training was not associated with a significant change in quality of life. CONCLUSIONS: Supervised AT or CAST are effective modes of exercise to improve VO2peak and muscle strength in older women with heart failure. However, the improvements in VO2peak and muscle strength are not maintained with unsupervised exercise training.     

Effects of aerobic exercise training and irbesartan on blood pressure and heart rate variability in patients with chronic obstructive pulmonary disease

BACKGROUND AND OBJECTIVES:

The present pilot study was undertaken to evaluate the efficacy of an aerobic exercise training (AET) program alone or combined with an antihypertensive agent (irbesartan) to reduce blood pressure (BP) and enhance heart rate variability (HRV) in chronic obstructive pulmonary disease patients.

METHODS:

Twenty-one patients were randomly assigned to a double-blind treatment with exercise and placebo (n=11) or exercise and irbesartan (n=10). Subjects underwent 24 h BP monitoring and 24 h electrocardiographic recording before and after the 12-week AET. HRV was investigated using three indexes from the power spectral analysis and three indexes calculated from the time domain. The AET program consisted of exercising on a calibrated ergocycle for 30 min three times per week. Five patients in the placebo group were excluded during follow-up because they were not compliant.

RESULTS:

There was no change in 24 h systolic and diastolic BP before (130±14 mmHg and 70±3 mmHg, respectively) and after (128±8 mmHg and 70±8 mmHg, respectively) exercise training in the placebo group, whereas in the irbesartan group systolic and diastolic BP decreased from 135±9 mmHg and 76±9 mmHg to 126±12 mmHg and 72±8 mmHg, respectively (P<0.02). There were no changes in HRV parameters in either group.

CONCLUSIONS:

The present study suggests that a 12-week AET program is not associated with a significant reduction in BP or enhancement in HRV, whereas an AET program combined with irbe-sartan is associated with a reduction in 24 h BP.     

Nonselective beta-adrenergic blocking agent, carvedilol, improves arterial baroflex gain and heart rate variability in patients with stable chronic heart failure

OBJECTIVES: The purpose of this study was to investigate in a case-controlled study whether carvedilol increased baroreflex sensitivity and heart rate variability (HRV). BACKGROUND: In chronic heart failure (CHF), beta-adrenergic blockade improves symptoms and ventricular function and may favorably affect prognosis. Although beta-blockade therapy is supposed to decrease myocardial adrenergic activity, data on restoration of autonomic balance to the heart and, particularly, on vagal reflexes are limited. METHODS: Nineteen consecutive patients with moderate, stable CHF (age 54 +/- 7 years, New York Heart Association [NYHA] class II to III, left ventricular ejection fraction [LVEF] 24 +/- 6%), treated with optimized conventional medical therapy, received carvedilol treatment. Controls with CHF were selected from our database on the basis of the following matching criteria: age +/- 3 years, same NYHA class, LVEF +/- 3%, pulmonary wedge pressure +/- 3 mm Hg, peak volume of oxygen +/- 3 ml/kg/min, same therapy. All patients underwent analysis of baroreflex sensitivity (phenylephrine method) and of HRV (24-h Holter recording) at baseline and after six months. RESULTS: Beta-blockade therapy was associated with a significant improvement in symptoms (NYHA class 2.1 +/- 0.4 vs. 1.8 +/- 0.5, p < 0.01), systolic and diastolic function (LVEF 23 +/- 7 vs. 28 +/- 9%, p < 0.01; pulmonary wedge pressure 17 +/- 8 vs. 14 +/- 7 mm Hg, p < 0.05) and mitral regurgitation area (7.0 +/- 5.1 vs. 3.6 +/- 3.0 cm2, p < 0.01). No significant differences were observed in either clinical or hemodynamic indexes in control patients. Phenylephrine method increased significantly after carvedilol (from 3.7 +/- 3.4 to 7.1 +/- 4.9 ms/mm Hg, p < 0.01) as well as RR interval (from 791 +/- 113 to 894 +/- 110 ms, p < 0.001), 24-h standard deviation of normal RR interval and root mean square of successive differences (from 56 +/- 17 to 80 +/- 28 ms and from 12 +/- 7 to 18 +/- 9 ms, all p < 0.05), while all parameters remained unmodified in controls. During a mean follow-up of 19 +/- 8 months a reduced number of cardiac events (death plus heart transplantation, 58% vs. 31%) occurred in those patients receiving beta-blockade. CONCLUSIONS: Besides the well-known effects on ventricular function, treatment with carvedilol in CHF restores both autonomic balance and the ability to increase reflex vagal activity. This protective mechanism may contribute to the beneficial effect of beta-blockade treatment on prognosis in CHF.