Dissociation between exertional symptoms and circulatory function in patients with heart failure

Identification of three mechanistic pathways for iron-deficient heart failure

Current understanding of iron-deficient heart failure is based on blood tests that are thought to reflect systemic iron stores, but the available evidence suggests greater complexity. The entry and egress of circulating iron is controlled by erythroblasts, which (in severe iron deficiency) will sacrifice erythropoiesis to supply iron to other organs, e.g. the heart. Marked hypoferraemia (typically with anaemia) can drive the depletion of cardiomyocyte iron, impairing contractile performance and explaining why a transferrin saturation < ≈15%-16% predicts the ability of intravenous iron to reduce the risk of major heart failure events in long-term trials (Type 1 iron-deficient heart failure). However, heart failure may be accompanied by intracellular iron depletion within skeletal muscle and cardiomyocytes, which is disproportionate to the findings of systemic iron biomarkers. Inflammation- and deconditioning-mediated skeletal muscle dysfunction-a primary cause of dyspnoea and exercise intolerance in patients with heart failure-is accompanied by intracellular skeletal myocyte iron depletion, which can be exacerbated by even mild hypoferraemia, explaining why symptoms and functional capacity improve following intravenous iron, regardless of baseline haemoglobin or changes in haemoglobin (Type 2 iron-deficient heart failure). Additionally, patients with advanced heart failure show myocardial iron depletion due to both diminished entry into and enhanced egress of iron from the myocardium; the changes in iron proteins in the cardiomyocytes of these patients are opposite to those expected from systemic iron deficiency. Nevertheless, iron supplementation can prevent ventricular remodelling and cardiomyopathy produced by experimental injury in the absence of systemic iron deficiency (Type 3 iron-deficient heart failure). These observations, taken collectively, support the possibility of three different mechanistic pathways for the development of iron-deficient heart failure: one that is driven through systemic iron depletion and impaired erythropoiesis and two that are characterized by disproportionate depletion of intracellular iron in skeletal and cardiac muscle. These mechanisms are not mutually exclusive, and all pathways may be operative at the same time or may occur sequentially in the same patients.

Locomotor and respiratory muscle abnormalities in HFrEF and HFpEF

Heart failure (HF) is a chronic and progressive syndrome affecting worldwide billions of patients. Exercise intolerance and early fatigue are hallmarks of HF patients either with a reduced (HFrEF) or a preserved (HFpEF) ejection fraction. Alterations of the skeletal muscle contribute to exercise intolerance in HF. This review will provide a contemporary summary of the clinical and molecular alterations currently known to occur in the skeletal muscles of both HFrEF and HFpEF, and thereby differentiate the effects on locomotor and respiratory muscles, in particular the diaphragm. Moreover, current and future therapeutic options to address skeletal muscle weakness will be discussed focusing mainly on the effects of exercise training.

Age, sex, endurance capacity, and chronic heart failure affect central and peripheral factors of oxygen uptake measured by non-invasive and continuous technologies: support of pioneer work using invasive or non-continuous measures

Introduction

It is known that maximum oxygen uptake depends on age, sex, endurance capacity, and chronic heart failure. However, due to the required invasive or often applied non-continuous approaches, less is known on underlying central and peripheral factors. Thus, this study aimed to investigate the effects of age, sex, endurance capacity, and chronic heart failure on non-invasively and continuously measured central and peripheral factors of oxygen uptake.

Methods

15 male children (11 ± 1 years), 15 male (24 ± 3 years) and 14 female recreationally active adults (23 ± 2 years), 12 male highly trained endurance athletes (24 ± 3 years), and 10 male elders (59 ± 6 years) and 10 chronic heart failure patients (62 ± 7 years) were tested during a cardiopulmonary exercise test on a cycling ergometer until exhaustion for: blood pressure, heart rate, stroke volume, cardiac output, cardiac power output, vastus lateralis muscle oxygen saturation, and (calculated) arterio-venous oxygen difference. For the non-invasive and continuous measurement of stroke volume and muscle oxygen saturation, bioreactance analysis and near-infrared spectroscopy were used, respectively. A two-factor repeated measure ANOVA and partial eta-squared effect sizes (η p 2 ) were applied for statistical analyses at rest, 80, and 100% of oxygen uptake.

Results

For the age effect, there were statistically significant group differences for all factors (p ≤ .033; η p 2 ≥ .169 ). Concerning sex, there were group differences for all factors (p ≤ .010; η p 2 ≥ .223 ), except diastolic blood pressure and heart rate (p ≥ .698; η p 2 ≤ .006 ). For the effect of endurance capacity, there were no group differences for any of the factors (p ≥ .065; η p 2 ≤ .129 ). Regarding chronic heart failure, there were group differences for the heart rate and arterio-venous oxygen difference (p ≤ .037; η p 2 ≥ .220 ).

Discussion

Age, sex, endurance capacity, and chronic heart failure affect central and peripheral factors of oxygen uptake measured by non-invasive and continuous technologies. Since most of our findings support pioneer work using invasive or non-continuous measures, the validity of our applied technologies is indirectly confirmed. Our outcomes allow direct comparison between different groups serving as reference data and framework for subsequent studies in sport science and medicine aiming to optimise diagnostics and interventions in athletes and patients.

Reducing Pulmonary Capillary Wedge Pressure During Exercise Exacerbates Exertional Dyspnea in Patients With Heart Failure With Preserved Ejection Fraction: Implications for V˙/Q˙ Mismatch

BACKGROUND

The primary cause of dyspnea on exertion in heart failure with preserved ejection fraction (HFpEF) is presumed to be the marked rise in pulmonary capillary wedge pressure during exercise; however, this hypothesis has never been tested directly. Therefore, we evaluated invasive exercise hemodynamics and dyspnea on exertion in patients with HFpEF before and after acute nitroglycerin (NTG) treatment to lower pulmonary capillary wedge pressure.

RESEARCH QUESTION

Does reducing pulmonary capillary wedge pressure during exercise with NTG improve dyspnea on exertion in HFpEF?

STUDY DESIGN AND METHODS

Thirty patients with HFpEF performed two invasive 6-min constant-load cycling tests (20 W): one with placebo (PLC) and one with NTG. Ratings of perceived breathlessness (0-10 scale), pulmonary capillary wedge pressure (right side of heart catheter), and arterial blood gases (radial artery catheter) were measured. Measurements of V˙/Q˙ matching, including alveolar dead space (Vdalv; Enghoff modification of the Bohr equation) and the alveolar-arterial Po2 difference (A-aDO2; alveolar gas equation), were also derived. The ventilation (V˙e)/CO2 elimination (V˙co2) slope was also calculated as the slope of the V˙e and V˙co2 relationship, which reflects ventilatory efficiency.

RESULTS

Ratings of perceived breathlessness increased (PLC: 3.43 ± 1.94 vs NTG: 4.03 ± 2.18; P = .009) despite a clear decrease in pulmonary capillary wedge pressure at 20 W (PLC: 19.7 ± 8.2 vs NTG: 15.9 ± 7.4 mm Hg; P < .001). Moreover, Vdalv (PLC: 0.28 ± 0.07 vs NTG: 0.31 ± 0.08 L/breath; P = .01), A-aDO2 (PLC: 19.6 ± 6.7 vs NTG: 21.1 ± 6.7; P = .04), and V˙e/V˙co2 slope (PLC: 37.6 ± 5.7 vs NTG: 40.2 ± 6.5; P < .001) all increased at 20 W after a decrease in pulmonary capillary wedge pressure.

INTERPRETATION

These findings have important clinical implications and indicate that lowering pulmonary capillary wedge pressure does not decrease dyspnea on exertion in patients with HFpEF; rather, lowering pulmonary capillary wedge pressure exacerbates dyspnea on exertion, increases V˙/Q˙ mismatch, and worsens ventilatory efficiency during exercise in these patients. This study provides compelling evidence that high pulmonary capillary wedge pressure is likely a secondary phenomenon rather than a primary cause of dyspnea on exertion in patients with HFpEF, and a new therapeutic paradigm is needed to improve symptoms of dyspnea on exertion in these patients.

Functional and Metabolic Imaging in Heart Failure with Preserved Ejection Fraction: Promises, Challenges, and Clinical Utility

Heart failure with preserved ejection fraction (HFpEF) is recognised as an increasingly prevalent, morbid and burdensome condition with a poor outlook. Recent advances in both the understanding of HFpEF and the technological ability to image cardiac function and metabolism in humans have simultaneously shone a light on the molecular basis of this complex condition of diastolic dysfunction, and the inflammatory and metabolic changes that are associated with it, typically in the context of a complex patient. This review both makes the case for an integrated assessment of the condition, and highlights that metabolic alteration may be a measurable outcome for novel targeted forms of medical therapy. It furthermore highlights how recent technological advancements and advanced medical imaging techniques have enabled the characterisation of the metabolism and function of HFpEF within patients, at rest and during exercise.

Use of patient-reported outcomes in heart failure: from clinical trials to routine practice

Heart failure (HF) is a complex syndrome that affects mortality/morbidity and acts at different levels in the patient's life, resulting in a drastic impairment in multiple aspects of daily activities (e.g. physical, mental/emotional, and social) and leading to a reduction in quality of life. The definition of disease status and symptom severity has been traditionally based on the physician assessment, while the patient's experience of disease has been long overlooked. The active participation of patients in their own care is necessary to better understand the perception of disease and the multiple aspects of life affected, and to improve adherence to treatments. Patient-reported outcomes (PROs) aim to switch traditional care to a more patient-centred approach. Although PROs demonstrated precision in the evaluation of disease status and have a good association with prognosis in several randomized controlled trials, their implementation into clinical practice is limited. This review discusses the modalities of use of PROs in HF, summarizes the most largely adopted PROs in HF care, and provides an overview on the application of PROs in trials and the potential for their transition to clinical practice. By discussing the advantages and the disadvantages of their use, the reasons limiting their application in daily clinical routine, and the strategies that may promote their implementation, this review aims to foster the systematic integration of the patient's standpoint in HF care.

Exercise-Induced Pulmonary Hypertension: A Valid Entity or Another Factor of Confusion?

Exercise-induced pulmonary hypertension EIPH has been defined as an increase in mean pulmonary arterial pressure (mPAP) during exercise in otherwise normal values at rest. EIPH reflects heart and/or lung dysfunction and may precede the development of manifest pulmonary hypertension (PH) in a proportion of patients. It is also associated with decreased life expectancy in patients with heart failure with reduced ejection fraction (HFrEF) or left ventricle (LV) valvular diseases. Diastolic dysfunction exacerbated during exercise relates to increased LV filling pressure and left atrial pressure (LAP). In this context backward, transmitted pressure alone or accompanied with backward blood flow promotes EIPH. The gold standard of EIPH assessment remains the right heart catheterization during exercise, which is an accurate but invasive method. Alternatively, non-invasive diagnostic modalities include exercise stress echocardiography (ESE) and cardiopulmonary exercise testing (CPET). Both diagnostic tests are performed under gradually increasing physical stress using treadmill and ergo-cycling protocols. Escalating workload during the exercise is analogous to the physiological response to real exercise. The results of the latter techniques show good correlation with invasive measurements, but they suffer from lack of validation and cut-off value determination. Although it is not officially recommended, there are accumulated data supporting the importance of EIPH diagnosis in the assessment of other mild/subclinical or probably fatal diseases in patients with latent PH or heart failure or LV valvular disease, respectively. Nevertheless, larger, prospective studies are required to ensure its role in clinical practice.

Patients report more severe daily limitations than recognized by their physicians

BACKGROUND

Patient limitations guide selection of heart failure therapies, for which indications often specify New York Heart Association Class.

OBJECTIVES

To determine the extent of patient-reported limitations during daily activities and compare to New York Heart Association class assigned by providers during the same visit, and to left ventricular ejection fraction (LVEF) group.

METHODS AND RESULTS

While waiting for their appointment, 948 patients on return visits to an ambulatory HF clinic completed a written questionnaire assessing specific activity limitations, which were compared to physician-assigned NYHA class during the same visit. Patient-reported limitation to perform daily activity ranged from 25% for bathing to 61% for yardwork or housework and 71% for jogging or hurrying. Most patients who did not report limitations to perform daily life activities were correctly classified as NYHA I by the physicians (76%), but 12% of the 376 patients classified as NYHA I reported limitations to showering or bathing and 73% reported limitations while doing yardwork or house work. Limitation to walking was reported by 172 patients (50%) classified as class II. Limitations to walking one block were most common in patients with LVEF ≥40% compared to patients with LVEF <40%, and least commonly, in HF with better EF (improved from 31 ± 13 to 52 ± 7).

CONCLUSIONS

Activity limitations are commonly reported by ambulatory HF patients, but underestimated by physicians. It is not clear how this should guide therapy validated for NYHA class but focused activity questions may merit wider use to track limitations and improvement in ambulatory HF.

Test-Retest Reliability of Non-Invasive Cardiac Output Measurement during Exercise in Healthy Volunteers in Daily Clinical Routine

Background

Thoracic bioreactance (TB), a noninvasive method for the measurement of cardiac output (CO), shows good test-retest reliability in healthy adults examined under research and resting conditions.

Objective

In this study, we evaluate the test-retest reliability of CO and cardiac power (CPO) output assessment during exercise assessed by TB in healthy adults under routine clinical conditions.

Methods

25 test persons performed a symptom-limited graded cycling test in an outpatient office on two different days separated by one week. Cardiorespiratory (power output, VO_2peak) and hemodynamic parameters (heart rate, stroke volume, CO, mean arterial pressure, CPO) were measured at rest and continuously under exercise using a spiroergometric system and bioreactance cardiograph (NICOM, Cheetah Medical).

Results

After 8 participants were excluded due to measurement errors (outliers), there was no systematic bias in all parameters under all conditions (effect size: 0.2-0.6). We found that all noninvasively measured CO showed acceptable test-retest-reliability (intraclass correlation coefficient: 0.59-0.98; typical error: 0.3-1.8). Moreover, peak CPO showed better reliability (intraclass correlation coefficient: 0.80-0.85; effect size: 0.9-1.1) then the TB CO, thanks only to the superior reliability of MAP (intraclass correlation coefficient: 0.59-0.98; effect size: 0.3-1.8).

Conclusion

Our findings preclude the clinical use of TB in healthy subject population when outliers are not identified.

Impact of Pump Speed on Hemodynamics With Exercise in Continuous Flow Ventricular Assist Device Patients

At fixed speed, the spontaneous increase in pump flow accompanying exercise in patients with continuous flow left ventricular assist devices (cfLVADs) is slight in comparison to normal physiologic response, limiting exercise capacity. We systematically exercised 14 patients implanted with an isolated HeartWare HVAD undergoing routine right heart catheterization at baseline and at maximal safe pump speed. In addition to hemodynamics, mixed venous oxygen saturation (SvO2), echocardiography and noninvasive mean arterial pressure, and heart rate were measured. Significantly greater pump flows were achieved with maximum pump speed compared with baseline speed at rest (mean ± standard deviation [SD]: 5.0 ± 0.7 vs. 4.6 ± 0.8 L/min) and peak exercise (6.7 ± 1.0 vs. 5.9 ± 0.9 L/min, p = 0.001). Pulmonary capillary wedge pressure was significantly reduced with maximum pump speed compared to baseline pump speed at rest (10 ± 4 vs. 15 ± 5 mmHg, p < 0.001) and peak exercise (27 ± 8 vs. 30 ± 8 mmHg, p = 0.002). Mixed venous oxygen saturation decreased with exercise (p < 0.001) but was unaffected by changes in pump speed. In summary, although higher pump speeds synergistically augment the increase in pump flow associated with exercise and blunt the exercise-induced rise in left heart filling pressures, elevated filling pressures and markedly diminished SvO2 persist at maximal safe pump speed, suggesting that physiologic flow increases are not met by isolated cfLVADs in the supported failing heart.

Haemodynamics, dyspnoea, and pulmonary reserve in heart failure with preserved ejection fraction

Aims

Increases in left ventricular filling pressure are a fundamental haemodynamic abnormality in heart failure with preserved ejection fraction (HFpEF). However, very little is known regarding how elevated filling pressures cause pulmonary abnormalities or symptoms of dyspnoea. We sought to determine the relationships between simultaneously measured central haemodynamics, symptoms, and lung ventilatory and gas exchange abnormalities during exercise in HFpEF.

Methods and results

Subjects with invasively-proven HFpEF (n = 50) and non-cardiac causes of dyspnoea (controls, n = 24) underwent cardiac catheterization at rest and during exercise with simultaneous expired gas analysis. During submaximal (20 W) exercise, subjects with HFpEF displayed higher pulmonary capillary wedge pressures (PCWP) and pulmonary artery pressures, higher Borg perceived dyspnoea scores, and increased ventilatory drive and respiratory rate. At peak exercise, ventilation reserve was reduced in HFpEF compared with controls, with greater dead space ventilation (higher VD/VT). Increasing exercise PCWP was directly correlated with higher perceived dyspnoea scores, lower peak exercise capacity, greater ventilatory drive, worse New York Heart Association (NYHA) functional class, and impaired pulmonary ventilation reserve.

Conclusion

This study provides the first evidence linking altered exercise haemodynamics to pulmonary abnormalities and symptoms of dyspnoea in patients with HFpEF. Further study is required to identify the mechanisms by which haemodynamic derangements affect lung function and symptoms and to test novel therapies targeting exercise haemodynamics in HFpEF.

Resting and exercise haemodynamics in relation to six-minute walk test in patients with heart failure and preserved ejection fraction

AIMS

Patients with heart failure and preserved ejection fraction (HFpEF) are characterized by functional impairment and an abnormal haemodynamic response to exercise. The six-minute walk test (6MWT) serves as a standardized test for functional capacity quantification in heart failure patients, and is associated with cardiovascular outcomes. However, as the association between 6MWT and haemodynamic parameters during rest and exercise in HFpEF patients is unknown, we sought to elucidate this relationship.

METHODS AND RESULTS

Overall, 64 patients enrolled in the REDUCE LAP-HF trial completed a 6MWT at baseline. Univariate and multivariable linear regression models were used to assess the associations between 6MWT and measured or derived haemodynamic variables at baseline, during light/moderate exercise (20 W), and at peak supine exercise. The average 6MWT distance was 318 ± 106 m. At rest, in a multivariable model, only pulmonary capillary wedge pressure (PCWP) was significantly associated with 6MWT [coefficient: -5.4, 95% confidence interval (CI) -10.4, -0.5, P = 0.033]. During light/moderate exercise, mean pulmonary artery pressure was associated with 6MWT in a multivariable model (coefficient: -3.5, 95% CI -6.8, -0.3, P = 0.033). During peak exercise, central venous pressure, cardiac index (CI), and PCWP/CI correlated with 6MWT; however, workload corrected PCWP was the only variable independently associated with 6MWT (coefficient: -0.8, 95% CI -1.3, -0.4, P < 0.001). The variance in 6MWT was modestly explained by measured or derived haemodynamic variables at rest or at any stage of exercise (r²  = 7-17%).

CONCLUSION

Workload corrected PCWP correlated best with 6MWT performance in HFpEF patients. Baseline haemodynamic variables were modestly correlated with 6MWT, suggesting that 6MWT performance in HFpEF patients may be significantly influenced by extra-cardiac factors.

Physical function and exercise training in older patients with heart failure

Heart failure (HF) is a common end point for numerous cardiovascular conditions, including coronary artery disease, valvular disease, and hypertension. HF predominantly affects older individuals (aged ≥70 years), particularly those living in developed countries. The pathophysiological sequelae of HF progression have a substantial negative effect on physical function. Diminished physical function in older patients with HF, which is the result of combined disease-related and age-related effects, has important implications on health. A large body of research spanning several decades has demonstrated the safety and efficacy of regular physical activity in improving outcomes among the HF population, regardless of age, sex, or ethnicity. However, patients with HF, especially those who are older, are less likely to engage in regular exercise training compared with the general population. To improve initiation of regular exercise training and subsequent long-term compliance, there is a need to rethink the dialogue between clinicians and patients. This Review discusses the need to improve physical function and exercise habits in patients with HF, focusing on the older population.

Assessment of Diastolic Function in Congenital Heart Disease

Diastolic function is an important component of left ventricular (LV) function which is often overlooked. It can cause symptoms of heart failure in patients even in the presence of normal systolic function. The parameters used to assess diastolic function often measure flow and are affected by the loading conditions of the heart. The interpretation of diastolic function in the context of congenital heart disease requires some understanding of the effects of the lesions themselves on these parameters. Individual congenital lesions will be discussed in this paper. Recently, load-independent techniques have led to more accurate measurements of ventricular compliance and remodeling in heart disease. The combination of inflow velocities and tissue Doppler measurements can be used to estimate diastolic function and LV filling pressures. This review focuses on diastolic function and assessment in congenital heart disease.

TONOMETRIA DA ARTÉRIA FEMORAL EM CÃES SAUDÁVEIS E COM DOENÇA VALVAR MITRAL DEGENERATIVA CRÔNICA

Resumo A tonometria de aplanação é um método capaz de aferir a pressão sanguínea dentro de uma artéria. Além de especulações sobre a razão das variações de amplitude das ondas de pulso femoral em cães com doença degenerativa valvar mitral crônica (DVMDC), em medicina, já está demonstrado que muitos sintomas de insuficiência cardíaca em pessoas são atribuíveis a anormalidades funcionais vasculares periféricas e não estão muito associados com parâmetros hemodinâmicos centrais. Desse modo, este trabalho teve por objetivo verificar a aplicabilidade da tonometria vascular em cães, avaliar as medidas de pressão na artéria femoral de cães saudáveis e compará-las com as de cães com regurgitação mitral devido à DVMDC. Os parâmetros tonométricos ainda foram correlacionados com índices cardíacos obtidos pela ecocardiografia. Os dados foram obtidos de 10 cães saudáveis e de 10 cães com DVMDC com regurgitação mitral à ecocardiografia. Observou-se que o período de pré-condução da onda de pulso foi significantemente menor nos animais com DVMDC do que nos saudáveis. Houve uma forte correlação entre a pressão sistólica da artéria femoral com parâmetros determinantes da função sistólica do coração nos animais saudáveis. A tonometria por aplanação da artéria femoral mostrou-se uma técnica aplicável em cães.

Assessing quality-of-life outcomes in cardiovascular clinical research

The field of quality-of-life (QOL) measurement grew out of attempts in the 1960s and 1970s to connect the ever-increasing levels of public expenditure on technology-based health care for chronic diseases with evidence of the benefits and harms to patients. Most of the concepts, methods, and standards for measuring QOL were derived from psychometrics, but the degree to which current tools adhere to these methods varies greatly. Despite the importance of QOL, patient-reported outcomes are not measured in most cardiovascular clinical trials. Lack of familiarity with QOL measures and their interpretation, and unrealistic expectations about the information these measures can provide, are obstacles to their use. Large clinical trials of revascularization therapy for coronary artery disease and medical treatments for heart failure show small-to-moderate QOL effects, primarily detected with disease-specific instruments. Larger treatment effects, seen in trials of device therapy for heart failure and ablation therapy for atrial fibrillation, have been detected with both generic and disease-specific instruments. A large gap remains between the parameters currently being measured in clinical research and the data needed to incorporate the 'patient's voice' into therapeutic decision-making.

Heart failure induces changes in acid-sensing ion channels in sensory neurons innervating skeletal muscle

Heart failure is associated with diminished exercise capacity, which is driven, in part, by alterations in exercise-induced autonomic reflexes triggered by skeletal muscle sensory neurons (afferents). These overactive reflexes may also contribute to the chronic state of sympathetic excitation, which is a major contributor to the morbidity and mortality of heart failure. Acid-sensing ion channels (ASICs) are highly expressed in muscle afferents where they sense metabolic changes associated with ischaemia and exercise, and contribute to the metabolic component of these reflexes. Therefore, we tested if ASICs within muscle afferents are altered in heart failure. We used whole-cell patch clamp to study the electrophysiological properties of acid-evoked currents in isolated, labelled muscle afferent neurons from control and heart failure (induced by myocardial infarction) mice. We found that the percentage of muscle afferents that displayed ASIC-like currents, the current amplitudes, and the pH dose-response relationships were not altered in mice with heart failure. On the other hand, the biophysical properties of ASIC-like currents were significantly different in a subpopulation of cells (40%) from heart failure mice. This population displayed diminished pH sensitivity, altered desensitization kinetics, and very fast recovery from desensitization. These unique properties define these channels within this subpopulation of muscle afferents as being heteromeric channels composed of ASIC2a and -3 subunits. Heart failure induced a shift in the subunit composition of ASICs within muscle afferents, which significantly altered their pH sensing characteristics. These results might, in part, contribute to the changes in exercise-mediated reflexes that are associated with heart failure.

The small-molecule fast skeletal troponin activator, CK-2127107, improves exercise tolerance in a rat model of heart failure

Heart failure-mediated skeletal myopathy, which is characterized by muscle atrophy and muscle metabolism dysfunction, often manifests as dyspnea and limb muscle fatigue. We have previously demonstrated that increasing Ca(2+) sensitivity of the sarcomere by a small-molecule fast skeletal troponin activator improves skeletal muscle force and exercise performance in healthy rats and models of neuromuscular disease. The objective of this study was to investigate the effect of a novel fast skeletal troponin activator, CK-2127107 (2-aminoalkyl-5-N-heteroarylpyrimidine), on skeletal muscle function and exercise performance in rats exhibiting heart failure-mediated skeletal myopathy. Rats underwent a left anterior descending coronary artery ligation, resulting in myocardial infarction and a progressive decline in cardiac function [left anterior descending coronary artery heart failure (LAD-HF)]. Compared with sham-operated control rats, LAD-HF rat hindlimb and diaphragm muscles exhibited significant muscle atrophy. Fatigability was increased during repeated in situ isokinetic plantar flexor muscle contractions. CK-2127107 produced a leftward shift in the force-Ca(2+) relationship of skinned, single diaphragm, and extensor digitorum longus fibers. Exercise performance, which was assessed by rotarod running, was lower in vehicle-treated LAD-HF rats than in sham controls (116 ± 22 versus 193 ± 31 seconds, respectively; mean ± S.E.M.; P = 0.04). In the LAD-HF rats, a single oral dose of CK-2127107 (10 mg/kg p.o.) increased running time compared with vehicle treatment (283 ± 47 versus 116 ± 22 seconds; P = 0.0004). In summary, CK-2127107 substantially increases exercise performance in this heart failure model, suggesting that modulation of skeletal muscle function by a fast skeletal troponin activator may be a useful therapeutic in heart failure-associated exercise intolerance.

Cardiac resynchronisation therapy: a randomised trial of factory or echocardiographic settings for optimum response

BACKGROUND

We aimed to assess whether echocardiographically-optimised atrioventricular (AV) and interventricular (VV) delay programming provided any additional benefit over standard settings following biventricular pacemaker implantation in patients with advanced heart failure.

METHODS

Paired data were collected on 22 patients (aged 67.5 ± 8.3 years, 16 male) with refractory heart failure, NYHA class III/IV symptoms, sinus rhythm, LBBB and a broad QRS complex >120 ms. All patients underwent implantation of a biventricular pacemaker and were randomised to eight weeks of factory pacing mode (Mode 1) or echocardiographically-guided pacing mode (Mode 2), followed by eight weeks in the alternate mode, in a randomised blinded crossover design.

RESULTS

Peak oxygen consumption, 6 min walk distance, NYHA class and quality of life scores improved after biventricular pacing, but no significant difference was found between the two modes, with the exception of peak oxygen consumption score (baseline: 14.8 ± 0.9, Mode 1: 14.6 ± 1.2, Mode 2: 16.1 ± 1.2 mL/kg/min), which was better in Mode 2 than Mode 1 (p 0.003).

CONCLUSION

Transthoracic echocardiographic optimisation of AV and VV delays following biventricular pacing may offer additional clinical benefit in an unselected group of patients when compared with factory settings.

Patients with heart failure in the "intermediate range" of peak oxygen uptake: additive value of heart rate recovery and the minute ventilation/carbon dioxide output slope in predicting mortality

PURPOSE

While patients with heart failure who achieve a peak oxygen uptake (peak VO2) of 10 mL·kg(-1)·min(-1) or less are often considered for intensive surveillance or intervention, those achieving 14 mL·kg(-1)·min(-1) or more are generally considered to be at lower risk. Among patients in the "intermediate" range of 10.1 to 13.9 mL·kg(-1)·min(-1), optimally stratifying risk remains a challenge.

METHODS

Patients with heart failure (N = 1167) referred for cardiopulmonary exercise testing were observed for 21 ± 13 months. Patients were classified into 3 groups of peak VO2 (≤10, 10.1-13.9, and ≥14 mL·kg(-1)·min(-1)). The ability of heart rate recovery at 1 minute (HRR1) and the minute ventilation/carbon dioxide output (VE/VCO2) slope to complement peak VO2 in predicting cardiovascular mortality were determined.

RESULTS

Peak VO2, HRR1 (<16 beats per minute), and the VE/VCO2 slope (>34) were independent predictors of mortality (hazard ratio 1.6, 95% CI: 1.2-2.29, P = .006; hazard ratio 1.7, 95% CI: 1.1-2.5, P = .008; and hazard ratio 2.4, 95% CI: 1.6-3.4, P < .001, respectively). Compared with those achieving a peak VO2 ≥ 14 mL·kg(-1)·min(-1), patients within the intermediate range with either an abnormal VE/VCO2 slope or HRR1 had a nearly 2-fold higher risk of cardiac mortality. Those with both an abnormal HRR1 and VE/VCO2 slope had a higher mortality risk than those with a peak VO2 ≤ 10 mL·kg(-1)·min(-1). Survival was not different between those with a peak VO2 ≤ 10 mL·kg(-1)·min(-1) and those in the intermediate range with either an abnormal HRR1 or VE/VCO2 slope.

CONCLUSIONS

HRR1 and the VE/VCO2 slope effectively stratify patients with peak VO2 within the intermediate range into distinct groups at high and low risk.

Determining the effectiveness of torasemide and furosemide in heart failure: design of a randomised comparison using the regenstrief medical record system

OBJECTIVE

A state-of-the-art clinical computing system was investigated to test the hypothesis of whether a completely and predictably absorbed loop diuretic (torasemide) offers clinical advantages over a diuretic that is poorly and erratically absorbed (furosemide).

PATIENTS

We enrolled 234 patients with heart failure into this randomised, prospective, open-label study of the effectiveness and cost effectiveness of torasemide and furosemide with a comprehensive electronic medical record called the Regenstrief Medical Record System (RMRS) serving as the primary data repository.

METHODS

The RMRS contained patient data for physician visits, emergency department visits, hospitalisations, laboratory tests, prescription medications, and in- and outpatient service charges. Because these patient data were captured during the course of routine care, there was much efficiency in study data collection and few associated costs. Before the study began, ready access to the RMRS data permitted characterisation of the target study population and an accurate sample size calculation. During the study, programs contained within the RMRS identified patients for recruitment, preserved randomisation, and alerted investigators to important patient events. Quality-of-life instruments programmed into notebook computers were loaded with available RMRS data and then supplemented with primary collection data, thereby permitting paperless data entry.

CONCLUSION

The computing infrastructure used for this study has permitted us to examine an interface between clinical pharmacology and outcomes research within the realm of medical informatics.

Repeated assessment of physical biomeasures or blood biomarkers for the definition of volume status and cardiac loading in LVSD

The application of biomarker technology can be usefully implemented in areas where current techniques are inadequate and where a clinical issue, which affects outcome, can be defined. The definition of the loading status of the heart where there is pre-existent impairment of contractile function is a key target. Heart failure is a complex clinical presentation with many varied etiologies, but at the essence of its successful management is the reliable definition of cardiac volume loading. Traditional and many current technological measures are applied to define this relationship, yet their accuracy and performance in individual patients is either basically inadequate or poorly understood and applied. There is a wide range of both physical measurements and blood biomarkers that can be considered to better define this key issue in patients with ventricular systolic impairment. Their performance is considered in detail in this review.

Muscular arterial impedance in dogs with chronic degenerative mitral valve disease

Systemic vascular impedance represents the retrograde strength of the blood flow to the left ventricle, thus it is one of the main compounds of afterload. Mitral regurgitation is markedly sensitive to afterload alterations. The purpose of this study was to evaluate muscular arterial impedance in dogs with chronic degenerative mitral valve disease (CDMVD) by use of duplex Doppler ultrasonography (DDU), since its technique there was not used before to determine impedance index in dogs with CDMVD. For this purpose, ten healthy dogs and ten dogs with CDMVD were used. Some parameters related to blood flow impedance in the common femoral artery were measured by DDU: pulsatility index (PI), resistance index (RI), high-resistance index (HRI), and acceleration velocity (AC) and deceleration velocity (DC) of the systolic peak. The results showed that RI and HRI were significantly higher in animals with CDMVD than in healthy animals. These findings showed that DDU provides quantitative data related to vascular impedance. Broader studies may therefore provide new aspects related to physiopathology and therapy in CDMVD patients.

Cardiac power index: staging heart failure for mechanical circulatory support

Cardiac power output has been shown to quantify cardiac reserve. Cardiac reserve is defined as the difference between basal and maximal cardiac performance. We compared cardiac power index to other commonly used hemodynamic parameters to validate its usefulness to stage heart failure patients and determine the optimal time for implantation of mechanical circulatory support. A retrospective study of twenty-eight heart failure patients implanted with mechanical circulatory support was analyzed at three levels of drug therapy. Subjects were further separated into two categories: survived versus deceased. Cardiac power index was the only statistically significant hemodynamic parameter that identified cardiac reserve (p<0.05) in this patient population. These results showed that a cardiac power index at or below 0.34 Watts/m(2) resulted in increased mortality rate, ninety days post-implantation.

CONCLUSION

Cardiac reserve was a determinant of post-device survival; therefore, these data suggest that device implantation should occur prior to the 0.34 Watts/m(2) threshold.

Prediction of true circulatory decompensation in chronic heart failure for optimal timing of mechanical circulatory support: non-invasive arterial-ventricular coupling

Background: Prospective comparative studies to predict the risk of hemodynamic deterioration in patients referred for transplantation were performed on the basis of standard invasive and non-invasive data and new wave intensity (WI) parameters. Methods and results: Study Group 1 consisted of 151 consecutive outpatients (age 48.7 ± 12 years; 110 men) with end-stage dilative cardiomyopathy. Group 2, consisting of 11 consecutive patients (age 50 ± 11 years; 6 men) with sinus rhythm and “true” decompensation, was used to create “critical values” of WI. There were no demographic or somatic (weight and height) differences between the groups. The follow-up period of ambulatory patients was 31 ± 8 months. Non-invasive WI was studied in the common carotid artery. Complete invasive and non-invasive data were also recorded on the day of investigation. During follow-up 44 pts were lost; there were 15 cardiac deaths (10%), life-saving ventricular assist device implantation in 10 (6.6%) and transplantation in 19 (12.7%). For statistical purposes this group was named the “events” Group B (n = 44). A predisposing factor for events (death, “true” decompensation and “urgent” transplantation in ambulatory patients) was low first peak (“cut-off value” assessed in Group 2 < 4100 mmHg*s³) (OR 45.6, CI 14.5–143.3, p < 0.001). Less powerful predictors of the risk of deterioration were pulmonary capillary pressure (PCP), diastolic pulmonary artery pressure (PAP) and E/A mitral wave relation (p = 0.05). Conclusions: The new ventricular-arterial coupling parameter 1st peak of WI can potentially be used to distinguish patients at high risk for true deterioration and death. This parameter can be used to predict the need for assist device implantation.

Exercise intolerance

Exercise intolerance is the primary symptom of chronic diastolic heart failure. It is part of the definition of heart failure and is intimately linked to its pathophysiology. Further, exercise intolerance affects the diagnosis and prognosis of heart failure. In addition, understanding the mechanisms of exercise intolerance can lead to developing and testing rational treatments for heart failure. This article focuses on the fundamental principles of exercise physiology and on the assessment, pathophysiology, and potential treatment of exercise intolerance in diastolic heart failure.

Effects of sedation with acepromazine maleate and buprenorphine hydrochloride on femoral artery blood flow in healthy dogs

The purpose of this study was to qualify and quantify the femoral artery blood flow by duplex Doppler ultrasonography (DDU) in healthy dogs, before and after the administration of a combination of acepromazine maleate and buprenorphine hydrochloride (ACP-BPN). Seven healthy adult mongrel dogs and three adult beagles were used. Heart rate, arterial blood pressure and measurement of femoral artery blood flow by DDU were also recorded. The DDU measurements were: femoral artery diameter (FAD), peak systolic velocity (PSV), early retrograde (EDV) and end diastolic velocities (EnDV), mean velocity (BMV), pulsatility index (PI), flow velocity integral (FVI) and femoral blood flow (FBF). After 30 min, combination ACP-BPN was administered intramuscularly, and all the measurements were recorded again. The ACP-BPN protocol induced a significant decrease in systolic, mean, and diastolic arterial blood pressure, and heart rate. A significant increase in peak systolic velocity and integral flow velocity integral of the femoral blood were obtained. The Doppler spectra of the blood flow in the femoral artery revealed a spectral dispersion pattern after ACP-BPN administration in all the dogs. These results demonstrate that despite quantitative and qualitative changes, the overall femoral blood flow (FBF) is not significantly modified.

Combined aerobic and resistance exercise program improves task performance in patients with heart failure

OBJECTIVES

To assess the effects of a home-based aerobic and resistance training program on the physical function of adults with New York Heart Association (NYHA) class II and III patients and systolic heart failure (HF).

DESIGN

Randomized controlled trial.

SETTING

Home based.

PARTICIPANTS

Stable patients (N=24; mean age, 60 ± 10 y; left ventricular ejection fraction, 25% ± 9%; 50% white; 50% women) with New York Heart Association (NYHA) classes II and III (NYHA class III, 58%) systolic heart failure (HF).

INTERVENTION

A 12-week progressive home-based program of moderate-intensity aerobic and resistance exercise. Attention control wait list participants performed light stretching and flexibility exercises.

MAIN OUTCOME MEASURES

A 10-item performance-based physical function measure, the Continuous Scale Physical Functional Performance test (CS-PFP10), was the major outcome variable and included specific physical activities measured in time to complete a task, weight carried during a task, and distance walked. Other measures included muscle strength, HRQOL (Minnesota Living With Heart Failure Questionnaire, Epworth Sleepiness Scale), functional capacity (Duke Activity Status Index), and disease severity (brain natriuretic peptide) levels.

RESULTS

After the exercise intervention, 9 of 10 specific task activities were performed more rapidly, with increased weight carried by exercise participants compared with the attention control wait list group. Exercise participants also showed significant improvements in CS-PFP10 total score (P<.025), upper and lower muscle strength, and HRQOL (P<.001) compared with the attention control wait list group. Adherence rates were 83% and 99% for the aerobic and resistance training, respectively.

CONCLUSIONS

Patients with stable HF who participate in a moderate-intensity combined aerobic and resistance exercise program may improve performance of routine physical activities of daily living by using a home-based exercise approach. Performance-based measures such as the CS-PFP10 may provide additional insights into physical function in patients with HF that more commonly used exercise tests may not identify. Early detection of subtle changes that may signal declining physical function that are amenable to intervention potentially may slow further loss of function in this patient population.

Oxygen uptake kinetics in chronic heart failure: clinical and physiological aspects

One of the hallmark symptoms of patients with chronic heart failure (CHF) is exercise intolerance. Therefore, exercise testing has become an important tool for the evaluation and monitoring of heart failure. Whereas the maximal aerobic capacity (peak VO(2)) is a reliable indicator of the severity and prognosis of heart failure, submaximal exercise parameters may be more closely related to the ability to perform daily activities. As such, oxygen (O(2)) uptake kinetics, describing the rate change of O(2) uptake during onset or recovery of submaximal constant-load exercise (O(2) onset and recovery kinetics, respectively), have been shown to be useful parameters for objectively evaluating the functional capacity of CHF patients. However, their evaluation in this population is not a routine part of daily clinical practice. Possible reasons for this include a lack of standardisation of the assessment methodology and a limited number of studies evaluating the clinical use of O(2) uptake kinetics in CHF patients. In addition, the pathophysiological mechanisms underlying the delay in O(2) uptake kinetics in these patients are not completely understood. This review discusses the current literature on the clinical potency and physiological determinants of O(2) uptake kinetics in CHF patients and provides directions for future research. (Neth Heart J 2009;17:238-44.Neth Heart J 2009;17:238-44.).

Serum 25-hydroxyvitamin D concentration is associated with functional capacity in older adults with heart failure

BACKGROUND

Vitamin D is a fat-soluble hormone necessary for calcium homeostasis. Recently, studies have demonstrated that vitamin D may be important to the health of the cardiovascular system.

METHODS

Adults ≥ 50 years of age with heart failure were recruited for assessment of serum 25-hydroxyvitamin D (25OHD) concentrations. Cardiopulmonary exercise testing was used to assess functional capacity. Proximal muscle strength was evaluated with a Biodex isokinetic dynamometer [corrected] (Biodex, Shirley, NY), and health status was assessed with the Kansas City Cardiomyopathy Questionnaire. Univariate associations between physical performance and health status measures and 25OHD followed by a linear regression model were used to study associations, adjusting for other potential explanatory variables.

RESULTS

Forty adults 67.8 ± 10.9 years of age (55% women and 57.5% African American) with mean ejection fraction 40% were analyzed (New York Heart Association class II in 70% and class III in 30%). Comorbidities included 77.5% hypertension and 47.5% diabetes. The mean 25OHD concentration was 18.5 ± 9.1 ng/mL, and mean peak Vo₂, 14 ± 4 mL/kg/min. In univariate regression analysis, 25OHD was positively associated with peak Vo₂ (P = .045). Multivariable regression analysis sustained positive association between 25OHD and peak Vo₂ (P = .044) after adjusting for age, race, and respiratory exchange ratio (adjusted R² = 0.32). Association between proximal muscle strength with the 25OHD concentration was not significant. The Kansas City Cardiomyopathy Questionnaire physical limitation domain score was negatively associated with 25OHD (P = .04) but was not sustained in multivariable analysis.

CONCLUSIONS

25-Hydroxyvitamin D may be an important marker or modulator of functional capacity in patients with heart failure. Randomized controlled trials are needed to assess the effect of vitamin D repletion on functional performance.

Influence of cardiomegaly on disordered breathing during exercise in chronic heart failure

AIMS

Heart failure (HF) patients breathe with a rapid shallow pattern during exercise. This study examined the relationship between cardiac size and tachypnoeic breathing in HF patients during exercise.

METHODS AND RESULTS

Thirty-seven HF patients [age = 55 ± 13 years, ejection fraction (EF) = 27 ± 10%, New York Heart Association (NYHA) class = 2.3 ± 1.2] and 42 controls (CTL) (age = 56 ± 14 years, EF = 63 ± 8%) were recruited. Participants underwent maximal exercise testing, pulmonary function testing, and chest radiography for calculation of total thoracic cavity volume (TTCV), diaphragm, heart, and lung volumes. Heart failure patients were divided into two groups: Group A = cardiac volume < median (n = 18) and Group B = cardiac volume ≥ median of the HF patients (n = 19). There was no difference between groups for TTCV (CTL = 8203 ± 1489 vs. Group A = 8694 ± 1249 vs. Group B = 8195 ± 1823 cm(3)). Cardiac volume was different between groups for both absolute (CTL = 630 ± 181 vs. Group A = 894 ± 186 vs. Group B = 1401 ± 382 cm(3), P< 0.001 for all comparisons) and %TTCV (CTL = 8 ± 2 vs. Group A = 10 ± 1 vs. Group A = 18 ± 5%, P< 0.001 for all comparisons). Similarly, total lung volume as a %TTCV was significantly different among the groups (CTL = 70 ± 4 vs. Group A = 65 ± 5 vs. Group A = 58 ± 7%, P< 0.01 for all comparisons). In HF patients, there was a trend (P = 0.10) towards an independent association between cardiac size and tidal volume (V(T)) at 75% of VO(2) peak whereas this relationship was statistically significant at VO(2) peak (P = 0.02) as patients with larger cardiac size had reduced V(T).

CONCLUSION

This study demonstrates the close relationship between cardiac size and breathing pattern during exercise in HF patients. These results suggest cardiac size may pose a significant constraint on the lungs during exercise and may contribute to tachypnoeic breathing.

Correlation of subjective questionnaires with cardiac function as determined by exercise testing in a pediatric population

BACKGROUND

Although exercise testing is an important objective method used to assess cardiopulmonary function, subjective assessment often is used as a proxy in the clinical setting. This study aimed to determine whether responses to a subjective functional capacity questionnaire administered to parents and patients in a pediatric exercise laboratory correlate with objective assessment of functional capacity, measured by peak oxygen consumption during maximal voluntary exercise testing.

METHODS

Subjective questionnaire responses and exercise test results collected over 10 years were retrospectively analyzed. Symptoms and physical capabilities were assessed using a 6-point Likert scale regarding the ability to attend school/work, walk, climb stairs, and run, as well as the frequency of fatigue, palpitations, and chest pain. Values of 0 to 3 were considered abnormal, whereas values of 4-5 were regarded as normal. Exercise testing was performed on a stationary cycle ergometer with a continuous ramping protocol. Heart rate and oxygen saturation were continuously monitored. Blood pressures and electrocardiograms (ECGs) were obtained at 2-min intervals. Metabolic gas analysis was performed using a breath-by-breath method. The results of the exercise testing were normalized for body size and expressed as a percentage of predicted peak oxygen consumption (%pVO(2)).

RESULTS

Very weak but statistically significant correlations (τ < 0.25; P < 0.05) between the scores of the school/work, walking, stair climbing, running, and fatigue items and %pVO(2) were found using Kendall's rank correlations.

CONCLUSIONS

The subjective Likert scales used to assess basic physical capacity and cardiac-associated symptoms have limited ability to predict actual functional capacity as measured by %pVO(2) achieved. The very weak rank-order correlation between %pVO(2) achieved and the subjective reporting of the ability to attend school/work, walk, climb stairs, and run has low clinical significance and will not be useful in predicting functional capacity within the clinic setting.

Resting measures and physiological responses to exercise for the determination of prognosis in patients with chronic heart failure: useful tools for clinical decision-making

Despite recent advances in the management of chronic heart failure (CHF), the prognosis of many of these patients remains dire. The need for an accurate prognosis in these patients has led to the identification of several indicators purported to represent the impact of the disease. Such indicators often are obtained at rest and are not always accurate at determining the clinical status of CHF patients. As a result, the relationship between prognostic indicators and clinical outcomes is frequently weak. On the other hand, physiological responses to acute exercise may unmask patients with the worst clinical status and identify those at increased risk of poor outcomes. Therefore, the present review appraises the value of several prognostic indicators for patients with CHF collected at rest and in response to exercise. In particular, it contrasts the value and accuracy of predictors of mortality widely used in clinical settings, such as oxygen uptake, ventilatory efficiency, and left ventricular ejection fraction, with new and more direct indicators of ventricular systolic and diastolic function.

Alterations in the large peripheral circulation in dogs with heart failure

The femoral artery is responsible for perfusion of a large muscular region that can be involved in the exercise intolerance shown by dogs with spontaneous heart failure. The objective of the present study was to evaluate blood flow in the femoral artery by transcutaneous duplex Doppler ultrasonography (TDU) in 50 healthy dogs and 50 dogs with spontaneous heart failure. The group of dogs with heart disease was divided according to the functional class of the heart failure. The TDU measurements were: peak systolic velocity (PSV), early retrograde (EDV) and end diastolic velocities (EnDV), mean velocity (MV), pulsatility index (PI), resistivity index (RI) and femoral flow volume (FFV). In healthy dogs, PSV and FFV were significantly higher than in dogs with heart disease. FFV was reduced mainly in patients with moderate and severe heart failure. TDU allowed for non-invasive detection and quantification of pathological alterations in peripheral hemodynamics.

Development and validation of a computer adaptive test for measuring dyspnea in heart failure

BACKGROUND

Dyspnea is a common symptom among patients with heart failure. Currently, there is no standardized, rapid, precise method to assess dyspnea.

METHODS AND RESULTS

From a review of the literature, we pooled questions from various questionnaires assessing dyspnea. A total of 201 patients with heart failure completed all questions in the preliminary item bank. Each item asks how much shortness of breath the patient had when doing an activity. Medical charts were reviewed for hospitalization within 1 or 3 months of completing the questions. We created a dyspnea item bank of 44 items. Computer adaptive tests (CAT) generated from this item bank can assess dyspnea by administering on average 10 questions. Simulation CAT scores were generated to compare with the item bank scores. The CAT scores had a correlation of 0.98 with item bank scores. Logistic regression models predicting the probability of being hospitalized from the dyspnea score were statistically significant (P < .05). A 5-point score increase was associated with a 32% increased odds of hospitalization in 1 month and a 20% increased odds of hospitalization in 3 months.

CONCLUSIONS

This computer-based tool for dyspnea assessment obtains similar precision to that of answering the entire dyspnea item bank with less patient burden.

Standardized peak exercise perception score: validation of a new index of effort perception

PURPOSE

Standardized peak exercise perception score (SPEPS) is an index representing patient effort perception defined as SPEPS = Borg/METs, where Borg is the Borg CR-10 at maximal exercise intensity and METs is maximal metabolic equivalents. The purpose of the study was to assess the validity of SPEPS in different patient groups and to examine its applicability for evaluation of exercise training outcomes.

METHODS

Patients (n = 17) with chronic heart failure (CHF, New York Heart Association [NYHA] II and III functional class; ejection fraction= 31 +/- 14%), 16 patients with chronic obstructive pulmonary disease (COPD, forced expiratory volume in 1 second - FEV(1)%= 51 +/- 14%), and 16 age- and body mass index-matched controls formed the primary study group. An additional 22 ambulatory patients with stable CHF (NYHA II-III) were randomized to training and nontraining groups to test the effect of 8 weeks' exercise training on SPEPS.

RESULTS

Patients showed reduced exercise capacity (V(O)(2), mL*kg(-1)* min(-1)) = 18.8 +/- 3.8 (CHF) vs 21.1 +/- 5.1 (COPD) vs 29.9 +/- 5.2 (control), corresponding to SPEPS values: 1.15 +/- 0.36 (CHF) vs 0.82 +/- 0.26 (COPD) vs 0.55 +/- 0.22 (control); P < .001. The reduction in SPEPS was the largest compared with the other tested parameters after training and correlated strongly with change in Minnesota Living with Heart Failure Questionnaire (rho= 0.75, P < .001).

CONCLUSION

SPEPS is a reliable new index for discriminating perceived exertion at the end of exercise test in different groups of patients, presenting both construct and concurrent validity. It is a potent parameter for evaluation of the outcomes in training programs.

What is treatment success in cardiac resynchronization therapy?

Cardiac resynchronization therapy (CRT) is an established treatment for symptomatic patients with heart failure, a prolonged QRS duration, and impaired left ventricular (LV) function. Identification of ‘responders’ and ‘non-responders’ to CRT has attracted considerable attention. The response to CRT can be measured in terms of symptomatic response or clinical outcome, or both. Alternatively, the response to CRT can be measured in terms of changes in surrogate measures of outcome, such as LV volumes, LV ejection fraction, invasive measures of cardiac performance, peak oxygen uptake, and neurohormones. This review explores whether these measures can be used in assessing the symptomatic and prognostic response to CRT. The role of these parameters to the management of individual patients is also discussed.

Comparison of right ventricular functional response to exercise in hypertrophic versus idiopathic dilated cardiomyopathy

Although the biventricular nature of the disease has been confirmed by morphologic studies, information on right ventricular (RV) function in hypertrophic cardiomyopathy (HC) is lacking. The aim of the study was to hemodynamically characterize RV performance in HC versus idiopathic dilated cardiomyopathy (IDC) during exercise. The hemodynamic data of 63 patients with HC who underwent hemodynamic exercise testing with thermodilution-derived assessment of RV ejection fraction were analyzed. The results were compared to a healthy control group (n = 20) and to patients with IDC (n = 86). The baseline RV ejection fraction was increased in the patients with HC compared to those with IDC (39 +/- 10% vs 33 +/- 12%; p = 0.002), but did not differ compared to controls (42 +/- 7% vs 39 +/- 10%; p = NS). An increase in end-diastolic volume from rest to exercise contributed to stroke volume augmentation in those with HC (121 +/- 38 vs 136 +/- 55 ml/m(2); p = 0.01) and control subjects (116 +/- 34 vs 138 +/- 31 ml/m(2); p = 0.002) but not in those with IDC (117 +/- 47 vs 120 +/- 52 ml/m(2); p = NS). At peak exercise the RV ejection fraction in those with HC was reduced compared to that in the controls (45 +/- 11% vs 59% +/- 9%; p <0.001), but it was increased compared to that in those with IDC (45 +/- 11% vs 35% +/- 11%; p <0.001). In conclusion, the extent of the pulmonary pressure increase was more pronounced in those with HC than in those with IDC, but the degree of functional impairment of the right ventricle was less severe, probably owing to its ability to recruit preload and contractile reserve with exercise.

Current controversies in heart failure with a preserved ejection fraction

Heart failure with a preserved ejection fraction is a fascinating and multifaceted condition that has provoked enormous debate and a wealth of mechanistic studies. Controversies exist with regard to its nomenclature. If its nomenclature is questioned, one can be certain the pathogenesis is ill understood. If the pathogenesis is disputed, the diagnosis becomes difficult and inconsistent. These diagnostic challenges result in inappropriate recruitment to clinical trials. Therefore, the trials may be underpowered and difficult to interpret. This paper examines contemporary theories of heart failure with a preserved ejection fraction, clarifies the controversies and attempts to resolve the divergences of opinion.

End-tidal CO2 pressure and cardiac performance during exercise in heart failure

INTRODUCTION

In patients with heart failure (HF), end-tidal CO2 pressure (PetCO2) is related to ventricular function at rest and has been shown to predict prognosis. However, little is known about the association between ventricular performance and PetCO2 responses to exercise.

METHODS

Forty-eight patients with HF and 13 normal subjects underwent cardiopulmonary exercise testing (CPX), while cardiac output and other hemodynamic measurements at rest and during exercise were obtained using a novel, noninvasive, bioreactance device based on assessment of relative phase shifts of electric currents injected across the thorax, heart rate, and ventricular ejection time. CPX responses and indices of cardiac performance were compared between normal subjects and HF patients achieving above and below a PetCO2 of 36 mm Hg at the ventilatory threshold (PetCO2@VT).

RESULTS

HF patients with an abnormal PetCO2@VT (<36 mm Hg) had a lower exercise capacity, a lower .VO2@VT, a higher .V_E/.VCO2 slope, and lower oxygen uptake efficiency slope (OUES) values compared with normal subjects and patients achieving a normal PetCO2@VT. Patients with reduced PetCO2@VT had lower peak cardiac output responses to exercise (20.0 +/- 10, 17.8 +/- 6, and 13.7 +/- 7 L x min for normal subjects and HF patients with normal and abnormal PetCO2 responses to exercise, respectively, P = 0.04). PetCO2@VT was inversely related to the .V_E/.VCO2 slope (r = -0.78, P < 0.001) and directly related to the OUES (r = 0.55, P < 0.001).

CONCLUSION

Reduced PetCO2 reflects impairments in the functional, ventilatory, and cardiac performance response to exercise in patients with HF. PetCO2 can supplement other clinical and CPX indices in the functional and prognostic evaluation of patients with HF.

Low-frequency electromyostimulation and chronic heart failure

Low-frequency electromyostimulation (EMS) acts on the skeletal muscle abnormalities that aggravate intolerance to effort in patients with chronic heart failure (CHF). It improves the oxidative capacity of muscles and thus enhances aerobic performance and physical capacity to almost the same degree, as does conventional physical training. No local or hemodynamic intolerance has been reported, even in cases of severe CHF. However, the presence of a pacemaker is one of the relative contra-indications (prior evaluation of tolerance is required), while that of an implanted defibrillator is one of the absolute contra-indications. EMS is an alternative to physical effort training when the latter is impossible due to a high degree of deconditioning or because there is a contra-indication, which may be temporary, due to the risk of acute decompensation and/or rhythm troubles. EMS can also be used in patients waiting for a heart transplant or in CHF patients who are unwilling to engage in physical activities. As EMS is not expensive and easy to set up, its use is likely to develop in the future.