Exertional dyspnoea in chronic heart failure: the role of the lung and respiratory mechanical factors

Low exertional inspiratory capacity is not related to dynamic inspiratory muscle weakness in heart failure

Reduction in inspiratory capacity (IC) during exercise has been reported in chronic heart failure (CHF). Since inspiratory muscle dysfunction may be present to a variable degree, the assumption that IC reduction during exercise represents an increase in end-expiratory lung volume must be made with caution. This interpretation is flawed if patients develop dynamic inspiratory muscle strength reduction, i.e., progressively lower esophageal (Pes) pressures as the IC maneuvers are repeated. Sixteen CHF patients and 9 age-matched controls performed an incremental exercise test with serial IC and respiratory pressure measurements. Regardless whether IC decreased or not with exercise (N = 4 and N = 12, respectively), Pes,IC remained stable. This was confirmed by similar Pes,sniff immediately upon exercise cessation (p > .05). No association was found between changes in IC and related Pes from rest to peak exercise. Owing to the lack of dynamic inspiratory muscle weakness, non-invasive indexes of lung mechanics can be reliably obtained from exercise IC in CHF.

Excess Ventilation in Chronic Obstructive Pulmonary Disease-Heart Failure Overlap. Implications for Dyspnea and Exercise Intolerance

RATIONALE

An increased ventilatory response to exertional metabolic demand (high [Formula: see text]e/[Formula: see text]co₂ relationship) is a common finding in patients with coexistent chronic obstructive pulmonary disease and heart failure.

OBJECTIVES

We aimed to determine the mechanisms underlying high [Formula: see text]e/[Formula: see text]co₂ and its impact on operating lung volumes, dyspnea, and exercise tolerance in these patients.

METHODS

Twenty-two ex-smokers with combined chronic obstructive pulmonary disease and heart failure with reduced left ventricular ejection fraction undertook, after careful treatment optimization, a progressive cycle exercise test with capillary (c) blood gas collection.

MEASUREMENTS AND MAIN RESULTS

Regardless of the chosen metric (increased [Formula: see text]e-[Formula: see text]co₂ slope, [Formula: see text]e/[Formula: see text]co₂ nadir, or end-exercise [Formula: see text]e/[Formula: see text]co₂), ventilatory inefficiency was closely related to Pc_CO2 (r values from -0.80 to -0.84; P < 0.001) but not dead space/tidal volume ratio. Ten patients consistently maintained exercise Pc_CO2 less than or equal to 35 mm Hg (hypocapnia). These patients had particularly poor ventilatory efficiency compared with patients without hypocapnia (P < 0.05). Despite the lack of between-group differences in spirometry, lung volumes, and left ventricular ejection fraction, patients with hypocapnia had lower resting Pa_CO2 and lung diffusing capacity (P < 0.01). Excessive ventilatory response in this group was associated with higher exertional Pc_O2. The group with hypocapnia, however, had worse mechanical inspiratory constraints and higher dyspnea scores for a given work rate leading to poorer exercise tolerance compared with their counterparts (P < 0.05).

CONCLUSIONS

Heightened neural drive promoting a ventilatory response beyond that required to overcome an increased "wasted" ventilation led to hypocapnia and poor exercise ventilatory efficiency in chronic obstructive pulmonary disease-heart failure overlap. Excessive ventilation led to better arterial oxygenation but at the expense of earlier critical mechanical constraints and intolerable dyspnea.

Rationales and choices for the treatment of patients with NYHA class II heart failure

Heart failure (HF) in the United States represents a significant burden for patients and a tremendous strain on the healthcare system. Patients receiving a diagnosis of HF can be placed into 1 of 4 New York Heart Association (NYHA) functional classifications; the greatest proportion of patients are in the NYHA class II category, which is defined as patients having a slight limitation of physical activity but who are comfortable at rest, and for whom ordinary physical activity results in symptoms of HF. Because the severity of NYHA class II HF may be perceived as mild or unalarming by this definition, the urgency to treat this type of HF may be overlooked. However, these patients are optimal candidates for active intervention because their HF is at a critical point on the disease progression continuum when untoward changes can be halted or reversed. This review discusses the physiological consequences of NYHA class II HF with reduced ejection fraction and describes recent clinical trials that have demonstrated a therapeutic benefit for patients in this population. In doing so, we hope to establish that patients with NYHA class II disease merit careful attention and to provide reassurance to the treating community that options are available for these patients.

Exertional dyspnoea in cardiorespiratory disorders: the clinical use of cardiopulmonary exercise testing

Is dyspnoea worth documenting and accurately assessing? The answer is undoubtedly yes, for at least the following reasons. 1) Activity-related dyspnoea is usually the earliest and most troublesome complaint for which patients with cardiopulmonary diseases seek medical attention. 2) This symptom progresses relentlessly as the underlying disease advances, leading invariably to avoidance of activity with consequent skeletal muscle deconditioning and an impoverished quality of life. 3) It is estimated that up to a quarter of the general population and half of severely ill patients are affected by it. 4) Dyspnoea is also an important predictor of quality of life, exercise tolerance and mortality in various conditions. In patients with chronic obstructive pulmonary disease (COPD), it has been shown to be a better predictor of mortality than forced expiratory volume in 1 s. In patients with heart disease referred for clinical exercise testing, it is a better predictor of mortality than angina. 5) Dyspnoea is also associated with decreased functional status and worse psychological health in older individuals living at home. 6) It is also a factor in the low adherence to exercise training programmes in sedentary adults and in patients with COPD. 7) The effective management of exertional dyspnoea remains a major challenge for caregivers and modern treatment strategies that are based on attempts to reverse the underlying chronic condition are only partially successful [1–7].

A series of articles on exertional dyspnoea in cardiorespiratory disorders begins in the European Respiratory Reviewhttp://ow.ly/fLT0300uHgw