Ventilatory and diffusion abnormalities in potential heart transplant recipients

Dynamic trend of lung fluid movement during exercise in heart failure: From lung imaging to alveolar-capillary membrane function

BACKGROUND

In chronic heart failure (HF), exercise-induced increase in pulmonary capillary pressure may cause an increase of pulmonary congestion, or the development of pulmonary oedema. We sought to assess in HF patients the exercise-induced intra-thoracic fluid movements, by measuring plasma brain natriuretic peptide (BNP), lung comets and lung diffusion for carbon monoxide (DLCO) and nitric oxide (DLNO), as markers of hemodynamic load changes, interstitial space and alveolar-capillary membrane fluids, respectively.

METHODS AND RESULTS

Twenty-four reduced ejection fraction HF patients underwent BNP, lung comets and DLCO/DLNO measurements before, at peak and 1 h after the end of a maximal cardiopulmonary exercise test. BNP significantly increased at peak from 549 (328-841) to 691 (382-1207, p < 0.0001) pg/mL and almost completely returned to baseline value 1 h after exercise. Comets number increased at peak from 9.4 ± 8.2 to 24.3 ± 16.7, returning to baseline (9.7 ± 7.4) after 1 h (p < 0.0001). DLCO did not change significantly at peak (from 18.01 ± 4.72 to 18.22 ± 4.73 mL/min/mmHg), but was significantly reduced at 1 h (16.97 ± 4.26 mL/min/mmHg) compared to both baseline (p = 0.0211) and peak (p = 0.0174). DLNO showed a not significant trend toward lower values 1 h post-exercise.

CONCLUSIONS

Moderate/severe HF patients have a 2-step intra-thoracic fluid movement with exercise: the first during active exercise, from the vascular space toward the interstitial space, as confirmed by comets increase, without any effect on diffusion, and the second, during recovery, toward the alveolar-capillary membrane, clearing the interstitial space but worsening gas diffusion.

Physiology of exercise and heart failure treatments: cardiopulmonary exercise testing as a tool for choosing the optimal therapeutic strategy

In the last decades, the pharmacological treatment of heart failure (HF) become more complex due to the availability of new highly effective drugs. Although the cardiovascular effects of HF therapies have been extensively described, less known are their effects on cardiopulmonary function considered as a whole, both at rest and in response to exercise. This is a 'holistic' approach to disease treatment that can be accurately evaluated by a cardiopulmonary exercise test. The aim of this paper is to assess the main differences in the effects of different drugs [angiotensin-converting enzyme (ACE)-inhibitors, Angiotensin II receptor blockers, β-blockers, Angiotensin receptor-neprilysin inhibitors, renal sodium-glucose co-transporter 2 inhibitors, iron supplementation] on cardiopulmonary function in patients with HF, both at rest and during exercise, and to understand how these differences can be taken into account when choosing the most appropriate treatment protocol for each individual patient leading to a precision medicine approach.

Hypoxaemia in patients with heart failure and preserved ejection fraction

AIMS

It is widely held that heart failure (HF) does not cause exertional hypoxaemia, based upon studies in HF with reduced ejection fraction, but this may not apply to patients with HF and preserved ejection fraction (HFpEF). Here, we characterize the prevalence, pathophysiology, and clinical implications of exertional arterial hypoxaemia in HFpEF.

METHODS AND RESULTS

Patients with HFpEF (n = 539) and no coexisting lung disease underwent invasive cardiopulmonary exercise testing with simultaneous blood and expired gas analysis. Exertional hypoxaemia (oxyhaemoglobin saturation <94%) was observed in 136 patients (25%). As compared to those without hypoxaemia (n = 403), patients with hypoxaemia were older and more obese. Patients with HFpEF and hypoxaemia had higher cardiac filling pressures, higher pulmonary vascular pressures, greater alveolar-arterial oxygen difference, increased dead space fraction, and greater physiologic shunt compared to those without hypoxaemia. These differences were replicated in a sensitivity analysis where patients with spirometric abnormalities were excluded. Regression analyses revealed that increases in pulmonary arterial and pulmonary capillary pressures were related to lower arterial oxygen tension (PaO2 ), especially during exercise. Body mass index (BMI) was not correlated with the arterial PaO2 , and hypoxaemia was associated with increased risk for death over 2.8 (interquartile range 0.7-5.5) years of follow-up, even after adjusting for age, sex, and BMI (hazard ratio 2.00, 95% confidence interval 1.01-3.96; p = 0.046).

CONCLUSION

Between 10% and 25% of patients with HFpEF display arterial desaturation during exercise that is not ascribable to lung disease. Exertional hypoxaemia is associated with more severe haemodynamic abnormalities and increased mortality. Further study is required to better understand the mechanisms and treatment of gas exchange abnormalities in HFpEF.

Association between DLCO index and the severity of heart failure: a cross-sectional study

BACKGROUND

The prognostic role of diffusing capacity of the lung for carbon monoxide (DLCO) in heart failure has not been thoroughly investigated. Therefore, this study aimed to evaluate DLCO variation in different systolic and diastolic heart failure stages.

METHODS

This was a prospective cross-sectional study on 51 patients with systolic (reduced LVEF) or diastolic (preserved LVEF) chronic heart failure (CHF). All patients underwent a standard DLCO test. The associations between the severity of heart failure and reduced carbon monoxide transfer factor (TLCO), carbon monoxide transfer coefficient (KCO), and alveolar volume (VA) were investigated. Data were analysed using SPSS software version 16. p-Values below 0.05 were considered statistically significant.

RESULTS

The mean age of participants was 59.29 ± 14.91 years, with 72% of the study population being male. Systolic heart failure was observed in 47% of patients, diastolic heart failure in 18%, and a mixed systolic and diastolic pattern in 35%. There were significant differences between TLCO percentage in patients with CHF types and the New York Heart Association (NYHA) functional classes (p = 0.042). Overall, an ejection fraction (EF) of less than 25% correlated with 3%, 53%, and 0.78 declines in TLCO, KCO%, and KCO index, respectively.

CONCLUSION

Despite the lack of statistically significant differences between DLCO indices and CHF severity, decreased DLCO parameters correlated with reduced EF. Therefore, DLCO testing might be helpful to predict HF severity.

Prognostic Role of Pulmonary Function in Patients With Heart Failure With Reduced Ejection Fraction

Background

Both ventilatory abnormalities and pulmonary hypertension (PH) are frequently observed in patients with heart failure with reduced ejection fraction. We aim to investigate the association between ventilatory abnormalities and PH in heart failure with reduced ejection fraction, as well as their prognostic impacts.

Methods and Results

A total of 440 ambulatory patients (age, 66.2±15.8 years; 77% men) with left ventricular ejection fraction ≤40% who underwent comprehensive echocardiography and spirometry were enrolled. Total lung capacity, forced vital capacity, and forced expiratory volume in the first second were obtained. Pulmonary arterial systolic pressure was estimated. PH was defined as a pulmonary arterial systolic pressure of >50 mm Hg. The primary end point was all‐cause mortality at 5 years. Patients with PH had significantly reduced total lung capacity, forced vital capacity, and forced expiratory volume in the first second. During a median follow‐up of 25.9 months, there were 111 deaths. After accounting for age, sex, body mass index, renal function, smoking, left ventricular ejection fraction, and functional capacity, total lung capacity (hazard ratio [HR] per 1 SD, 0.66; 95% CI per 1 SD, 0.46–0.96), forced vital capacity (HR per 1 SD, 0.64; 95% CI per 1 SD, 0.48–0.84), and forced expiratory volume in the first second (HR per 1 SD, 0.72; 95% CI per 1 SD, 0.53–0.98) were all significantly correlated with mortality in patients without PH. Kaplan‐Meier curve demonstrated impaired pulmonary function, defined as forced expiratory volume in the first second ≤58% of predicted or forced vital capacity ≤65% of predicted, was associated with higher mortality in patients without PH (HR, 2.85; 95% CI, 1.66–4.89), but not in patients with PH (HR, 1.05; 95% CI, 0.61–1.82).

Conclusions

Ventilatory abnormality was more prevalent in patients with heart failure with reduced ejection fraction with PH than those without. However, such ventilatory defects were related to long‐term survival only in patients without PH, regardless of their functional status.

Pulmonary Function Testing Pre-heart Transplant Predicts Posttransplant Survival

Supplemental Digital Content is available in the text.

Although pulmonary function testing (PFT) is typically performed for heart transplant evaluation, the prognostic utility of PFTs after transplantation is unknown. We evaluated whether PFT parameters were correlated with outcomes following heart transplantation.

Heart, lungs, and muscle interplay in worsening activity-related breathlessness in advanced cardiopulmonary disease

PURPOSE OF REVIEW

Activity-related breathlessness is a key determinant of poor quality of life in patients with advanced cardiorespiratory disease. Accordingly, palliative care has assumed a prominent role in their care. The severity of breathlessness depends on a complex combination of negative cardiopulmonary interactions and increased afferent stimulation from systemic sources. We review recent data exposing the seeds and consequences of these abnormalities in combined heart failure and chronic obstructive pulmonary disease (COPD).

RECENT FINDINGS

The drive to breathe increases ('excessive breathing') secondary to an enlarged dead space and hypoxemia (largely COPD-related) and heightened afferent stimuli, for example, sympathetic overexcitation, muscle ergorreceptor activation, and anaerobic metabolism (largely heart failure-related). Increased ventilatory drive might not be fully translated into the expected lung-chest wall displacement because of the mechanical derangements brought by COPD ('inappropriate breathing'). The latter abnormalities, in turn, negatively affect the central hemodynamics which are already compromised by heart failure. Physical activity then decreases, worsening muscle atrophy and dysfunction.

SUMMARY

Beyond the imperative of optimal pharmacological treatment of each disease, strategies to lessen ventilation (e.g., walking aids, oxygen, opiates and anxiolytics, and cardiopulmonary rehabilitation) and improve mechanics (heliox, noninvasive ventilation, and inspiratory muscle training) might mitigate the burden of this devastating symptom in advanced heart failure-COPD.

Low DLCO predicts all-cause hospital admissions in patients with reduced left ventricular ejection fraction or diastolic dysfunction

The diffusing capacity of the lung for carbon monoxide (D_LCO) can be decreased in many disease states, including COPD and interstitial lung disease [1, 2]. Low D_LCO can also be seen in those with clinically relevant congestive heart failure (CHF) due to its deleterious consequences on lung volumes, perfusion and gas exchange efficiency [3, 4]. Pulmonary function testing results are frequently available in patients with CHF. D_LCO measurements have previously been shown to impact exercise capacity in CHF patients with either reduced or preserved left ventricular ejection fraction (LVEF) [5–7]. Impaired D_LCO has also been suggested as a potential predictor of negative clinical outcomes in CHF [8]. We, therefore, aimed to determine if patients with reduced LVEF or isolated diastolic dysfunction on echocardiography and a low D_LCO are at a higher risk of hospital admissions than their counterparts with a preserved D_LCO. Confirmation of this hypothesis would support the need for closer monitoring of CHF patients who also present with a reduced D_LCO.

A low D_LCO should be valued as a predictor of all-cause hospital admissions in patients with reduced LVEF or isolated diastolic dysfunction. The severity of the impairment seen on D_LCO testing also appears to affect the risk of hospitalisation.https://bit.ly/3e4r8bH

Independent Prognostic Value of Pulmonary Diffusing Capacity in Nonsmoking Patients with Chronic Heart Failure

The diffusing capacity of the lung for carbon monoxide (DLCO) is indicative of the alveolar-capillary membrane function. A reduced DLCO is associated with poor prognosis in chronic heart failure (HF). However, the significance of DLCO as an independent prognostic predictor has not been established. Here, we aimed to determine the prognostic value of DLCO in patients with chronic HF.We enrolled 214 patients (139 females, mean age: 63 ± 16 years, left ventricular ejection fraction [LVEF]: 45 ± 21%) with stable chronic HF who underwent pulmonary function tests. Only never smokers were included in the analysis because smoking can decrease DLCO.During a median follow-up period of 2.1 years, 52 patients (24.3%) experienced cardiac events, including unplanned HF admissions, left ventricular assist device (LVAD) implantations, all-cause deaths, and cardiopulmonary arrests (CPAs). The median percent predicted DLCO (%DLCO) was 87.3%. In a Cox regression analysis, a %DLCO of ≤87.3% was independently associated with the cardiac events, even after adjusting for age, sex, systolic blood pressure (SBP), LVEF, anemia, brain natriuretic peptide, estimated glomerular filtration rate (eGFR), and prior HF admission (hazard ratio [HR]: 1.87, 95% confidence interval: 1.03-3.53, P = 0.030).A reduced DLCO is an independent predictor of poor prognosis in nonsmoking patients with chronic HF.

Lung diffusion capacity in advanced heart failure: relation to central haemodynamics and outcome

Aims

Patients with heart failure (HF) are known to have a reduced pulmonary diffusion capacity for carbon monoxide (D_LCO), but little is known about how lung function relates to central haemodynamics. The aim of this study was to investigate the association between haemodynamic variables and pulmonary diffusion capacity adjusted for alveolar volume in congestive HF patients and to analyse how predicted D_LCO/V_A affects mortality in relation to the haemodynamic status.

Methods and results

We retrospectively studied right heart catheterization (RHC) and lung function data on 262 HF patients (mean age 51 ± 13 years) with a left ventricular ejection fraction < 45% referred non‐urgently for evaluation for heart transplantation (HTX) or left ventricular assist device (LVAD). Univariate and multivariate linear regression models were constructed to examine the associations between predicted values of D_LCO/V_A, forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV₁), and haemodynamic parameters [pulmonary capillary wedge pressure (PCWP), central venous pressure, cardiac index, mean pulmonary artery pressure, and mean arterial pressure] as well as other factors known to affect lung function in HF. FEV₁ was reduced to <80% of predicted value in 55% of the population, and D_LCO/V_A was reduced in 63% of the population. D_LCO/V_A correlated positively with pulmonary capillary wedge pressure in both univariate and multivariate analyses for all included patients (P < 0.001 and P = 0.045, respectively) and a restricted population of patients with the shortest time between RHC and lung function testing (P = 0.005, P = 0.015). D_LCO/V_A predicted mortality in multivariate models [hazard ratio 1.5 (1.1–2.1)] but not the combined endpoint of death, LVAD implantation, or HTX. There was no significant correlation between haemodynamics and predicted FVC or FEV₁.

Conclusions

Pulmonary diffusion capacity correlates positively with left ventricular fillings pressures, and reduced values predict increased mortality in patients with HF. This might be driven by increased lung capillary volume in patients with pulmonary congestion.

Current challenges in managing comorbid heart failure and COPD

INTRODUCTION

Heart failure (HF) with reduced ejection fraction and chronic obstructive pulmonary disease (COPD) frequently coexist, particularly in the elderly. Given their rising prevalence and the contemporary trend to longer life expectancy, overlapping HF-COPD will become a major cause of morbidity and mortality in the next decade. Areas covered: Drawing on current clinical and physiological constructs, the consequences of negative cardiopulmonary interactions on the interpretation of pulmonary function and cardiopulmonary exercise tests in HF-COPD are discussed. Although those interactions may create challenges for the diagnosis and assessment of disease stability, they provide a valuable conceptual framework to rationalize HF-COPD treatment. The impact of COPD or HF on the pharmacological treatment of HF or COPD, respectively, is then comprehensively discussed. Authors finalize by outlining how the non-pharmacological treatment (i.e. rehabilitation and exercise reconditioning) can be tailored to the specific needs of patients with HF-COPD. Expert commentary: Randomized clinical trials testing the efficacy and safety of new medications for HF or COPD should include a sizeable fraction of patients with these coexistent pathologies. Multidisciplinary clinics involving cardiologists and respirologists trained in both diseases (with access to unified cardiorespiratory rehabilitation programs) are paramount to decrease the humanitarian and social burden of HF-COPD.

Cardiopulmonary Exercise Test as a Tool to Choose Therapy in Heart Failure

Heart failure treatment depends on several drugs, all providing improvement in outcome, but that cannot be realistically used all together in the same patient. It would be useful to have a tool that allows the arrangement of the most appropriate therapy cocktail for each patient. The aim of this article is to show the main differences in the effects of several drugs on cardiopulmonary function in patients with heart failure, both while resting and during exercise, and to discuss how these differences can be taken into account when choosing the most appropriate therapeutic protocol. In summary, angiotensin-converting enzyme inhibitors and angiotensin II receptor blockers act synergistically to increase exercise capacity and peak oxygen uptake, but through different mechanisms: the former improving lung diffusion and exercise ventilatory efficiency, an action that is counteracted by concomitant aspirin therapy, and the latter probably by improving muscle perfusion. As for β-blockers, nonselective compounds, such as carvedilol, improve ventilation efficiency on the one hand, but interfere with lung diffusion on the other, and they are probably less tolerated under hypoxic conditions. On the contrary, β₁-selective compounds, such as bisoprolol or nebivolol, have a neutral effect on both lung diffusion and ventilation efficiency. These observations could be the basis for the choice of pharmacological therapy in patients with heart failure.

Long-term outcomes and management of the heart transplant recipient

Cardiac transplantation remains the gold standard in the treatment of advanced heart failure. With advances in immunosuppression, long-term outcomes continue to improve despite older and higher risk recipients. The median survival of the adult after heart transplantation is currently 10.7 years. While early graft failure and multiorgan system dysfunction are the most important causes of early mortality, malignancy, rejection, infection, and cardiac allograft vasculopathy contribute to late mortality. Chronic renal dysfunction is common after heart transplantation and occurs in up to 68% of patients by year 10, with 6.2% of patients requiring dialysis and 3.7% undergoing renal transplant. Functional outcomes after heart transplantation remain an area for improvement, with only 26% of patients working at 1-year post-transplantation, and are likely related to the high incidence of depression after cardiac transplantation. Areas of future research include understanding and managing primary graft dysfunction and reducing immunosuppression-related complications.

Pulmonary function differences in patients with chronic right heart failure secondary to pulmonary arterial hypertension and chronic left heart failure

BACKGROUND

Pulmonary abnormalities are found in both chronic heart failure (CHF) and pulmonary arterial hypertension (PAH). The differences of pulmonary function in chronic left heart failure and chronic right heart failure are not fully understood.

MATERIAL AND METHODS

We evaluated 120 patients with stable CHF (60 with chronic left heart failure and 60 with chronic right heart failure). All patients had pulmonary function testing, including pulmonary function testing at rest and incremental cardiopulmonary exercise testing (CPX).

RESULTS

Patients with right heart failure had a significantly lower end-tidal partial pressure of CO2 (PetCO2), higher end-tidal partial pressure of O2 (PetO2) and minute ventilation/CO2 production (VE/VCO2) at rest. Patients with right heart failure had a lower peak PetCO2, and a higher peak dead space volume/tidal volume (VD/VT) ratio, peak PetO2, peak VE/VCO2, and VE/VCO2 slope during exercise. Patients with right heart failure had more changes in ∆PetCO2 and ∆VE/VCO2, from rest to exercise.

CONCLUSIONS

Patients with right heart failure had worse pulmonary function at rest and exercise, which was due to severe ventilation/perfusion (V/Q) mismatching, severe ventilation inefficiency, and gas exchange abnormality.

Prognostic value of resting pulmonary function in heart failure

BACKGROUND

The heart and lungs are intimately linked anatomically and physiologically, and, as a result, heart failure (HF) patients often develop changes in pulmonary function. This study examined the prognostic value of resting pulmonary function (PF) in HF.

METHODS AND RESULTS

In all, 134 HF patients (enrolled from January 1, 1999 Through December 31, 2005; ejection fraction (EF) = 29% ± 11%; mean age = 55 ± 12 years; 65% male) were followed for 67 ± 34 months with death/transplant confirmed via the Social Security Index and Mayo Clinic registry. PF included forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), diffusing capacity of the lungs for carbon monoxide (DLCO), and alveolar volume (VA). Patients were divided in tertiles according to PF with survival analysis via log-rank Mantel-Cox test with chi-square analysis. Groups for FVC included (1) >96%, (2) 96% to 81%, and (3) <81% predicted (chi-square = 18.9, P < 0.001). Bonferroni correction for multiple comparisons (BC) suggested differences between groups 1 and 3 (P < 0.001) and 2 and 3 (P = 0.008). Groups for FEV1 included (1) >94%, (2) 94% to 77%, and (3) <77% predicted (chi-square = 17.3, P <0.001). BC suggested differences between groups 1 and 3 (P <0.001). Groups for DLCO included (1) >90%, (2) 90% to 75%, and (3) <75% predicted (chi-square = 11.9, P = 0.003). BC suggested differences between groups 1 and 3 (P < 0.001). Groups for VA included (1) >97%, (2) 97% to 87%, and (3) <87% predicted (Chi-square = 8.5, P = 0.01). BC suggested differences between groups 1 and 2 (P = 0.014) and 1 and 3 (P = 0.003).

CONCLUSIONS

In a well-defined cohort of HF patients, resting measures of PF are predictive of all-cause mortality.

Abnormal Lung Function in Adults With Congenital Heart Disease: Prevalence, Relation to Cardiac Anatomy, and Association With Survival

Background—

Restrictive lung defects are associated with higher mortality in patients with acquired chronic heart failure. We investigated the prevalence of abnormal lung function, its relation to severity of underlying cardiac defect, its surgical history, and its impact on outcome across the spectrum of adult congenital heart disease.

Methods and Results—

A total of 1188 patients with adult congenital heart disease (age, 33.1±13.1 years) undergoing lung function testing between 2000 and 2009 were included. Patients were classified according to the severity of lung dysfunction based on predicted values of forced vital capacity. Lung function was normal in 53% of patients with adult congenital heart disease, mildly impaired in 17%, and moderately to severely impaired in the remainder (30%). Moderate to severe impairment of lung function related to complexity of underlying cardiac defect, enlarged cardiothoracic ratio, previous thoracotomy/ies, body mass index, scoliosis, and diaphragm palsy. Over a median follow-up period of 6.7 years, 106 patients died. Moderate to severe impairment of lung function was an independent predictor of survival in this cohort. Patients with reduced force vital capacity of at least moderate severity had a 1.6-fold increased risk of death compared with patients with normal lung function ( P =0.04).

Conclusions—

A reduced forced vital capacity is prevalent in patients with adult congenital heart disease; its severity relates to the complexity of the underlying heart defect, surgical history, and scoliosis. Moderate to severe impairment of lung function is an independent predictor of mortality in contemporary patients with adult congenital heart disease.

Lungs in heart failure

Lung function abnormalities both at rest and during exercise are frequently observed in patients with chronic heart failure, also in the absence of respiratory disease. Alterations of respiratory mechanics and of gas exchange capacity are strictly related to heart failure. Severe heart failure patients often show a restrictive respiratory pattern, secondary to heart enlargement and increased lung fluids, and impairment of alveolar-capillary gas diffusion, mainly due to an increased resistance to molecular diffusion across the alveolar capillary membrane. Reduced gas diffusion contributes to exercise intolerance and to a worse prognosis. Cardiopulmonary exercise test is considered the “gold standard” when studying the cardiovascular, pulmonary, and metabolic adaptations to exercise in cardiac patients. During exercise, hyperventilation and consequent reduction of ventilation efficiency are often observed in heart failure patients, resulting in an increased slope of ventilation/carbon dioxide (VE/VCO₂) relationship. Ventilatory efficiency is as strong prognostic and an important stratification marker. This paper describes the pulmonary abnormalities at rest and during exercise in the patients with heart failure, highlighting the principal diagnostic tools for evaluation of lungs function, the possible pharmacological interventions, and the parameters that could be useful in prognostic assessment of heart failure patients.

Muscle oxygen transport and utilization in heart failure: implications for exercise (in)tolerance

The defining characteristic of chronic heart failure (CHF) is an exercise intolerance that is inextricably linked to structural and functional aberrations in the O(2) transport pathway. CHF reduces muscle O(2) supply while simultaneously increasing O(2) demands. CHF severity varies from moderate to severe and is assessed commonly in terms of the maximum O(2) uptake, which relates closely to patient morbidity and mortality in CHF and forms the basis for Weber and colleagues' (167) classifications of heart failure, speed of the O(2) uptake kinetics following exercise onset and during recovery, and the capacity to perform submaximal exercise. As the heart fails, cardiovascular regulation shifts from controlling cardiac output as a means for supplying the oxidative energetic needs of exercising skeletal muscle and other organs to preventing catastrophic swings in blood pressure. This shift is mediated by a complex array of events that include altered reflex and humoral control of the circulation, required to prevent the skeletal muscle "sleeping giant" from outstripping the pathologically limited cardiac output and secondarily impacts lung (and respiratory muscle), vascular, and locomotory muscle function. Recently, interest has also focused on the dysregulation of inflammatory mediators including tumor necrosis factor-α and interleukin-1β as well as reactive oxygen species as mediators of systemic and muscle dysfunction. This brief review focuses on skeletal muscle to address the mechanistic bases for the reduced maximum O(2) uptake, slowed O(2) uptake kinetics, and exercise intolerance in CHF. Experimental evidence in humans and animal models of CHF unveils the microvascular cause(s) and consequences of the O(2) supply (decreased)/O(2) demand (increased) imbalance emblematic of CHF. Therapeutic strategies to improve muscle microvascular and oxidative function (e.g., exercise training and anti-inflammatory, antioxidant strategies, in particular) and hence patient exercise tolerance and quality of life are presented within their appropriate context of the O(2) transport pathway.

Clinical and radiographic predictors of GOLD-unclassified smokers in the COPDGene study

RATIONALE

A significant proportion of smokers have lung function impairment characterized by a reduced FEV(1) with a preserved FEV(1)/FVC ratio. These smokers are a poorly characterized group due to their systematic exclusion from chronic obstructive pulmonary disease (COPD) studies.

OBJECTIVES

To characterize the clinical, functional, and radiographic features of Global Initiative for Chronic Obstructive Lung Disease (GOLD)-Unclassified (FEV(1)/FVC ≥ 0.7 and FEV(1) < 80% predicted) and lower limits of normal (LLN)-unclassified (FEV(1)/FVC ≥ LLN and FEV(1) < LLN) subjects compared to smokers with normal lung function and subjects with COPD.

METHODS

Data from the first 2,500 subjects enrolled in the COPDGene study were analyzed. All subjects had 10 or more pack-years of smoking and were between the ages of 45 and 80 years. Multivariate regression models were constructed to determine the clinical and radiological variables associated with GOLD-Unclassified (GOLD-U) and LLN-Unclassified status. Separate multivariate regressions were performed in the subgroups of subjects with complete radiologic measurement variables available.

MEASUREMENTS AND MAIN RESULTS

GOLD-U smokers account for 9% of smokers in COPDGene and have increased body mass index (BMI), a disproportionately reduced total lung capacity, and a higher proportion of nonwhite subjects and subjects with diabetes. GOLD-U subjects exhibit increased airway wall thickness compared to smoking control subjects and decreased gas trapping and bronchodilator responsiveness compared to subjects with COPD. When LLN criteria were used to define the "unclassified" group, African American subjects were no longer overrepresented. Both GOLD-U and LLN-Unclassified subjects demonstrated a wide range of lung function impairment, BMI, and percentage of total lung emphysema.

CONCLUSIONS

Subjects with reduced FEV(1) and a preserved FEV(1)/FVC ratio are a heterogeneous group with significant symptoms and functional limitation who likely have a variety of underlying etiologies beyond increased BMI. Clinical trial registered with www.clinicaltrials.gov (NCT000608764).

Heart failure and the lung

Heart failure (HF) is a highly prevalent disease that leads to significant morbidity and mortality. There is increasing evidence that the symptoms of HF are exacerbated by its deleterious effects on lung function. HF appears to cause airway obstruction acutely and leads to impaired gas diffusing capacity and pulmonary hypertension in the longer term. It is postulated that this is the result of recurrent episodes of elevated pulmonary capillary pressure leading to pulmonary oedema and pulmonary capillary stress fracture, which produces lung fibrosis. It is likely that impaired lung function impairs the functional status of HF patients and makes them more prone to central sleep apnoea.

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.

Effects of respiratory muscle work on blood flow distribution during exercise in heart failure

Heart failure (HF) patients have a reduced cardiac reserve and increased work of breathing. Increased locomotor muscle blood flow demand may result in competition between respiratory and locomotor vascular beds. We hypothesized that HF patients would demonstrate improved locomotor blood flow with respiratory muscle unloading during activity. Ten patients (ejection fraction = 31 +/- 3%) and 10 controls (CTL) underwent two cycling sessions (60% peak work). Session 1 (S1): 5 min of normal breathing (NB), 5 min respiratory muscle unloading with a ventilator, and 5 min of NB. Session 2 (S2): 5 min NB, 5 min of respiratory muscle loading with inspiratory resistance, and 5 min of NB. Measurements included: leg blood flow (LBF, thermodilution), cardiac output (Q), and oesophageal pressure (P(pl), index of pleural pressure). S1: P(pl) was reduced in both groups (HF: 73 +/- 8%; CTL: 60 +/- 13%, P < 0.01). HF: Q increased (9.6 +/- 0.4 vs. 11.3 +/- 0.8 l min(-1), P < 0.05) and LBF increased (4.8 +/- 0.8 vs. 7.3 +/- 1.1 l min(-1), P < 0.01); CTL: no changes in Q (14.7 +/- 1.0 vs. 14.8 +/- 1.6 l min(-1)) or LBF (10.9 +/- 1.8 vs. 10.3 +/- 1.7 l min(-1)). S2: P(pl) increased in both groups (HF: 172 +/- 16%, CTL: 220 +/- 40%, P < 0.01). HF: no change was observed in Q(10.0 +/- 0.4 vs. 10.3 +/- 0.8 l min(-1)) or LBF (5.0 +/- 0.6 vs. 4.7 +/- 0.5 l min(-1)); CTL: increased (15.4 +/- 1.4 vs. 16.9 +/- 1.5 l min(-1), P < 0.01) and LBF remained unchanged (10.7 +/- 1.5 vs. 10.3 +/- 1.8 l min(-1)). These data suggest HF patients preferentially steal blood flow from locomotor muscles to accommodate the work of breathing during activity. Further, HF patients are unable to vasoconstrict locomotor vascular beds beyond NB when presented with a respiratory load.

Resting lung function in the assessment of the exercise capacity in patients with chronic heart failure

BACKGROUND

Despite the lung involvement in patients with chronic heart failure (CHF), the significance of lung function abnormalities to functional status in these patients is still controversial. We postulated that in patients with CHF, resting lung function assessment may provide information of clinical relevance on exercise capacity, expressed as peak oxygen uptake (VO2) and ventilatory response to CO2 production (VE/VCO2) during a maximal exercise.

METHODS

We studied 49 clinically stable patients with CHF (38 men, age range: 25-78 years) (New York Heart Association class range: I-IV) with left ventricular ejection fraction <40%. Patients with chronic obstructive pulmonary disease were excluded. Patients performed pulmonary function tests and maximal incremental exercise test.

RESULTS

Resting spirometry was related to the exercise capacity (P < 0.05), expressed as peak VO2. By means of receiver operating characteristic curve analysis, the forced expiratory volume at first second (FEV1) cutoff point, which better identified patients with a peak VO2 < or =14 mL/kg/min, was <79% of predicted value (0.79 sensitivity and 0.73 specificity). Resting lung diffusion capacity for carbon monoxide and end-tidal pressure of CO2 (PETCO2) were inversely correlated to VE/VCO2 (P < 0.01). The lung diffusion capacity for carbon monoxide and PETCO2 cutoff points, which better identified patients with VE/VCO2 value >34, were <58% of predicted (0.92 sensitivity and 0.42 specificity) and <33 mm Hg (0.67 sensitivity and 0.92 specificity), respectively.

CONCLUSIONS

In patients with CHF, resting lung function, including spirometry, lung diffusion capacity, and PETCO2, can provide clinically useful information on exercise capacity, by predicting peak VO2 and VE/VCO2 slope. The results of this study highlight the role of resting lung function in the assessment of the functional status of cardiac patients.

Alveolar gas diffusion abnormalities in heart failure

In heart failure (HF), development of pressure or volume overload of the lung microcirculation elicits a series of structural adaptations, whose functional correlate is an increased resistance to gas transfer across the alveolar-capillary membrane. Acutely, hydrostatic mechanical injury causes endothelial and alveolar cell breaks, impairment of the cellular pathways involved in fluid filtration and reabsorption, and resistance to gas transfer. This process, which is reminiscent of the so-called alveolar-capillary stress failure, is generally reversible. When the alveolar membrane is chronically challenged, tissue alterations are sustained and a typical remodeling process may take place that is characterized by fixed extracellular matrix collagen proliferation and reexpression of fetal genes. Remodeling leads to a persistent reduction in alveolar-capillary membrane conductance and lung diffusion capacity. Changes in gas transfer not only reflect the underlying lung tissue damage but also bring independent prognostic information and may play a role in the pathogenesis of exercise limitation and ventilatory abnormalities. They are not responsive to fluid withdrawal by ultrafiltration and tend to be refractory even to heart transplantation. Some drugs can be effective that modulate lung remodeling (eg, angiotensin-converting enzyme inhibitors, whose impact on the natural course of cardiac remodeling is well known) or that increase nitric oxide availability and nitric oxide-mediated pulmonary vasodilation (eg, type 5 phosphodiesterase inhibitors). This review focuses on the current knowledge of these topics.

Alveolar-capillary membrane conductance is the best pulmonary function correlate of exercise ventilation efficiency in heart failure patients

BACKGROUND

In heart failure (HF), changes in lung mechanics and gas diffusion are limiting factors to exercise. Their contribution to an increased exercise ventilation to CO2 production (VE/VCO2) slope is undefined.

METHODS

A total of 67 stable HF patients underwent cardiopulmonary exercise and pulmonary function tests, including forced vital capacity (FVC), forced expiratory volume in 1 s (FEV1), maximal voluntary ventilation (MVV), total lung capacity (TLC) and alveolar diffusing capacity with its subcomponents (alveolar-capillary membrane conductance (D(m)) and capillary blood volume (V(c))).

RESULTS

Patients showed a mild restrictive pattern (FEV1=85+/-15% and FVC=75+/-13% of normal predicted) and a moderate D(m) reduction (32+/-12 ml min(-1) mm Hg(-1)). Average peak VO(2) was 15.6+/-4.0 ml min(-1) kg(-1) and the VE/VCO2 slope was 39.6+/-11.0. At simple Spearman correlation analysis, all variables, but V(c), correlated with peak VO2; only D(m) correlated with VE/VCO2 slope. At partial Spearman correlation, all variables lost the peak VO2 correlation, and D(m) still inversely correlated with VE/VCO2 slope (r=-0.35; p=0.005). In patients with a high VE/VCO2 slope (cutoff value 34), despite comparable lung volumes, D(m) was significantly more depressed (30+/-13 vs. 35+/-10 ml min(-1) mm Hg(-1); p<0.01).

CONCLUSIONS

Pulmonary function tests and alveolar gas diffusing capacity poorly correlate with peak VO2. D(m) impairment rather than lung volumes correlates with exercise ventilation efficiency. This finding further adds to the pathophysiological relevance of an abnormal gas exchange in HF patients.

Pulmonary function changes associated with cardiomegaly in chronic heart failure

BACKGROUND

This study examined the influence of increased cardiac size on maximal lung volumes, forced expiratory airflows, and the diffusing capacity of the lungs in heart failure (HF) patients compared with controls.

METHODS AND RESULTS

Forty-one HF patients of New York Heart Association (NYHA) class: Group A = class I/II (n = 26) and Group B = class III/IV (n = 15) and an equal number matched controls (CTL) were recruited. Participants underwent echocardiography, spirometry, and posteroanterior and lateral chest radiographic evaluation (RAD) for volumetric estimation of the total thoracic cavity (TTC), diaphragm, heart, and lungs. Analysis of variance demonstrated no difference between groups for TTC volume (P = .63). RAD cardiac volumes (% TTC volume) were significantly different among all groups (P < .001). Echocardiograms determined left ventricular mass was elevated in the HF groups compared with the CTL group (P < .001) with no difference between HF groups. Lung volume (% TTC volume) was reduced as a function of disease severity (P < .001). RAD measures of cardiac volume demonstrated the strongest relationship with restrictive lung alterations (t-statistic = -5.627, P < .001 and t-statistic = -4.378, P < .001 for forced vital capacity and forced expiratory volume in 1 second, respectively).

CONCLUSIONS

These results suggest cardiac size may pose significant constraints on the lungs and likely plays a major role in the restrictive breathing patterns often reported in HF patients.

Why does chronic heart failure cause breathlessness and fatigue?

Traditional explanations for the symptoms of fatigue and breathlessness experienced by patients with chronic heart failure (CHF) focus on how reduced cardiac output on exercise leads to impaired skeletal muscle blood supply, thus causing fatigue, and on how the requirement for a raised left ventricular filling pressure to maintain cardiac output results in reduced pulmonary diffusion owing to interstitial edema, thus causing breathlessness. However, indices of left ventricular function relate poorly to exercise capacity and symptoms, suggesting that the origin of symptoms may lie elsewhere. There is a specific heart failure myopathy that is present early in the condition which may contribute largely to the sensation of fatigue. Receptors present in skeletal muscle sensitive to work (ergoreceptors) are overactive in patients with CHF, presumably as a consequence of the myopathy, and their activity is related both to the ventilatory response to exercise and breathlessness, and to the sympathetic overactivity of CHF. In the present paper, we review the systemic consequences of left ventricular dysfunction to understand how they relate to the symptoms of heart failure.

Chronic Respiratory Complications in Pediatric Heart Transplant Recipients

BACKGROUND

The frequency and spectrum of chronic respiratory complications in pediatric heart transplant recipients have not been extensively studied. The aim of this study was to describe the chronic respiratory complications in 126 consecutive pediatric heart transplant recipients.

METHODS

Retrospective review of medical records.

RESULTS

Between 1987 and 2005, 126 (64 males and 62 females) heart transplantations were performed at Freeman Hospital, Newcastle upon Tyne, United Kingdom. The median age at transplantation was 7.4 years (range, 0.1-17) and the median length of follow-up was 6.8 years (range, 0-18.2). Twenty-four patients have died, and 36 have been transferred to adult follow-up, leaving 66 under pediatric follow-up. Chronic respiratory complications have been documented in 33 children (50%). Bronchiectasis has been identified in 10 children, and 12 further children have had recurrent lower respiratory tract infections (without bronchiectasis) requiring long-term antibiotic prophylaxis. Of those with infectious complications, 81% underwent transplantation before 4 years and had deficiency of pneumococcal-specific antibody response. Obstructive sleep apnea has occurred in 5 children, sub-glottic stenosis has occurred in 3, and significant compression of the left main stem bronchus related to a disproportionately large donor heart has occurred in 2. One child had marked mosaic attenuation on chest computed tomography scan indicative of small airways disease.

CONCLUSION

Chronic respiratory complications are common in pediatric heart transplant recipients. The respiratory prognosis for this complex group of patients is usually good, but long-term follow-up by both a respiratory pediatrician and an immunologist is frequently required.

Statement on cardiopulmonary exercise testing in chronic heart failure due to left ventricular dysfunction: recommendations for performance and interpretation. Part I: definition of cardiopulmonary exercise testing parameters for appropriate use in chronic heart failure

Cardiopulmonary exercise testing (CPET) provides a global assessment of the integrated response to exercise involving the pulmonary, cardiovascular, haematopoietic, neuropsychological, and skeletal muscle systems. This information cannot be obtained through investigation of the individual organ systems in isolation. The non-invasive, dynamic physiological overview permits the evaluation of both submaximal and peak exercise responses, providing the physician with relevant information for clinical decision making. The use of CPET in management of the chronic heart failure patient is increasing with the understanding that resting pulmonary and cardiac function testing cannot reliably predict exercise performance and functional capacity and that, furthermore, overall health status and prognosis are predicted better by indices of exercise tolerance than by resting measurements. Our aim is to produce a statement which provides recommendations on the interpretation and clinical application of CPET in heart failure, based on contemporary scientific knowledge and technical advances: the focus is on clinical indications, issues of standardization, and interpretative strategies for CPET.

Competition for intrathoracic space reduces lung capacity in patients with chronic heart failure: a radiographic study

BACKGROUND

The purpose of this study was to determine the influence of changes in cardiac size on total lung volume in patients with chronic heart failure compared to control subjects.

METHODS

Forty-four patients and age-, gender-, and height-matched control participants were recruited. All participants underwent posteroanterior and lateral chest radiography for volumetric estimations of the total thoracic cavity (TTC), diaphragm, heart, and lungs. To assess the relationship between chronic heart failure severity and cardiac enlargement, patients with chronic heart failure were classified into groups based on New York Heart Association class, as follows: class I and II, n = 26 (group A); class III and IV, n = 18 (group B).

RESULTS

There was no difference between the groups for TTC volume (TTCV) [p = 0.56]. Cardiac volumes were significantly different between all groups for both the absolute volumes (p < 0.001) were calculated as a percentage of TTCV (p < 0.001), with the largest cardiac volumes in group B (twice the volume of healthy control subjects). When expressed as a percentage of TTCV, there also was a clear reduction in lung volumes as a function of disease severity (p < 0.001).

CONCLUSIONS

The present study demonstrates a close relationship between the severity of heart failure and cardiac size. These changes in cardiac size within a closed thoracic cavity may pose significant constraints on the lungs, resulting in reductions in lung volumes that likely play a major role in the restrictive breathing patterns often reported in patients with chronic heart failure.

Heart failure and chronic obstructive pulmonary disease: An ignored combination?

AIMS

To quantify the prevalence of heart failure and left ventricular systolic dysfunction (LVSD) in chronic obstructive pulmonary disease (COPD) patients and vice versa. Further, to discuss diagnostic and therapeutic implications of the co-existence of both syndromes.

METHODS AND RESULTS

We performed a Medline search from 1966 to March 2005. The reported prevalence of LVSD among COPD patients varied considerably, with the highest prevalence (10-46%) among those with an exacerbation. One single study assessed the prevalence of heart failure in COPD patients. A prevalence of 21% of previously unknown heart failure was reported in patients with a history of COPD or asthma. We did not find any report on COPD in heart failure or LVSD patients. Diagnosing heart failure in COPD patients or vice versa is complicated by overlap in signs and symptoms, and diminished diagnostic value of additional investigations. In general, pulmonary and heart failure 'drug cocktails' can be administered safely to patients with concomitant COPD and heart failure, although (short acting) beta2-adrenoreceptor agonists and digitalis have potentially deleterious effects on cardiac and pulmonary function, respectively.

CONCLUSION

Although knowledge about the prevalence of concomitant heart failure in COPD patients and vice versa is scarce, it seems that the combined presence is rather common. In view of diagnostic and therapeutic implications, more attention should be paid to the concomitant presence of both syndromes in clinical practice and research.

The reversibility of increased airways resistance in chronic heart failure measured by impulse oscillometry

BACKGROUND

Patients with chronic heart failure complain of breathlessness and fatigue on exercise. Airways resistance is increased and lung compliance is reduced in chronic heart failure patients. The aim of this study was to determine whether the pulmonary abnormalities are reversible and whether any improvements lead to changes to exercise capacity or symptoms.

METHODS

Twelve patients with stable chronic heart failure and 10 matched controls underwent repeated assessment of airways resistance using impulse oscillometry and peak exercise testing with metabolic gas exchange after receiving nebulized saline as placebo or combined salbutamol and ipratropium bromide in a double-blind crossover randomized fashion.

RESULTS

Patients had lower peak oxygen consumption and a steeper slope relating ventilation to carbon dioxide production than controls. Bronchodilators reduced peripheral airways resistance in patients (0.53 versus 0.38, P<.02) and controls (0.21 versus 0.19, P<.005) and increased measures of compliance in both groups. There was no effect on the peak oxygen consumption, exercise time, ventilation to carbon dioxide slope, or anaerobic threshold. There was an increase in peak tidal volume (VT) in both groups but this did not lead to an increase in peak ventilation. The slope relating symptoms to ventilation (ie, Borg/VE) was significantly reduced in the patients after bronchodilators (17%+/-8%, P<.05). The relationship between the improvement in VT and reduction in gradient of the Borg/VE slope was significant (r=.40, P<.05).

CONCLUSIONS

Nebulized bronchodilators improve airways resistance, lung reactance, and peak tidal volume during exercise in chronic heart failure but do not increase peak exercise capacity. They do, however, reduce the symptom of breathlessness.

Ventilatory Markers During Exercise for Congestive Heart Failure

The exaggerated ventilatory response in patients with heart failure is clearly multifactorial and complex beyond a mere reduction in pulmonary blood flow. Pulmonary dysfunction, including ventilation-perfusion mismatching, decreased lung compliance, restriction, airway obstruction, decreased diffusion capacity, and decreases in respiratory muscle strength and endurance, contributes to an inefficient breathing pattern and increased work of breathing. This is further compounded by the limited ability of the failing heart to meet the metabolic demands of the respiratory muscles, leading to underperfusion and ischemia.Although VO2max has important implications with regard to functional capacity, exercise test personnel must be knowledgeable concerning the clinical physiology of ventilation during exercise in the patient with heart failure. Ventilatory markers, as Arena and coworkers have demonstrated, are most indicative of disease severity and enhance the prognostic value of the test results.

The pulmonary manifestations of left heart failure

Determining whether a patient's symptoms are the result of heart or lung disease requires an understanding of the influence of pulmonary venous hypertension on lung function. Herein, we describe the effects of acute and chronic elevations of pulmonary venous pressure on the mechanical and gas-exchanging properties of the lung. The mechanisms responsible for various symptoms of congestive heart failure are described, and the significance of sleep-disordered breathing in patients with heart disease is considered. While the initial clinical evaluation of patients with dyspnea is imprecise, measurement of B-type natriuretic peptide levels may prove useful in this setting.

Exercise after heart transplantation

Exercise intolerance in heart transplant recipients (HTR) has a multifactorial origin, involving complex interactions among cardiac, neurohormonal, vascular, skeletal muscle and pulmonary abnormalities. However, the role of these abnormalities may differ as a function of time after transplantation and of many other variables. The present review is aimed at evaluating the role of cardiac, pulmonary and muscular factors in limiting maximal aerobic performance of HTR, and the benefits of chronic exercise. Whereas pulmonary function does not seem to affect gas exchange until a critical value of diffusing lung capacity is attained, cardiac and skeletal muscle function deterioration may represent relevant factors limiting maximal and submaximal aerobic performance. Cardiac function is mainly limited by chronotropic incompetence and diastolic dysfunction, whereas muscle activity seems to be limited by impaired oxygen supply as a consequence of the reduced capillary network. The latter may be due to either immunosuppressive regimen or deconditioning. Endurance and strength training may greatly improve muscle function and maximal aerobic performance of HTR, and may also reduce side effects of immunosuppressive therapy and control risk factors for cardiac allograft vasculopathy. For the above reasons exercise should be considered an important therapeutic tool in the long-term treatment of heart transplant recipients.

Does lung diffusion impairment affect exercise capacity in patients with heart failure?

OBJECTIVE

To determine whether there is a relation between impairment of lung diffusion and reduced exercise capacity in chronic heart failure.

DESIGN

40 patients with heart failure in stable clinical condition and 40 controls participated in the study. All subjects underwent standard pulmonary function tests plus measurements of resting lung diffusion (carbon monoxide transfer, TLCO), pulmonary capillary volume (VC), and membrane resistance (DM), and maximal cardiopulmonary exercise testing. In 20 patients and controls, the following investigations were also done: (1) resting and constant work rate TLCO; (2) maximal cardiopulmonary exercise testing with inspiratory O2 fractions of 0.21 and 0.16; and (3) rest and peak exercise blood gases. The other subjects underwent TLCO, DM, and VC measurements during constant work rate exercise.

RESULTS

In normoxia, exercise induced reductions of haemoglobin O2 saturation never occurred. With hypoxia, peak exercise uptake (peak O2) decreased from (mean (SD)) 1285 (395) to 1081 (396) ml/min (p < 0.01) in patients, and from 1861 (563) to 1771 (457) ml/min (p < 0.05) in controls. Resting TLCO correlated with peak O2 in heart failure (normoxia < hypoxia). In heart failure patients and normal subjects, TLCO and peak O2 correlated with O2 arterial content at rest and during peak exercise in both normoxia and hypoxia. TLCO, VC, and DM increased during exercise. The increase in TLCO was greater in patients who had a smaller reduction of exercise capacity with hypoxia. Alveolar-arterial O2 gradient at peak correlated with exercise capacity in heart failure during normoxia and, to a greater extent, during hypoxia.

CONCLUSIONS

Lung diffusion impairment is related to exercise capacity in heart failure.

Pulmonary function test abnormalities in pulmonary vascular disease and chronic heart failure

Diagnostic criteria based on pulmonary function testing for pulmonary vascular disease and CHF are imprecise. Although these tests constitute a necessary part of the work-up of a patient with dyspnea, additional studies are required to obtain a final diagnosis in the setting of cardiopulmonary vascular disease. In contrast, specific pulmonary function tests may offer an objective means of assessing severity of dysfunction resulting from pulmonary hypertension or CHE Serial measurements of pulmonary function offer insight into general and specific patterns of cardiopulmonary vascular disease and are useful in evaluating response to treatment.

Pulmonary function in patients with reduced left ventricular function: influence of smoking and cardiac surgery

STUDY OBJECTIVE

The impact of stable, chronic heart failure on baseline pulmonary function remains controversial. Confounding influences include previous coronary artery bypass or valve surgery (CABG), history of obesity, stability of disease, and smoking history.

DESIGN

To control for some of the variables affecting pulmonary function in patients with chronic heart failure, we analyzed data in four patient groups, all with left ventricular (LV) dysfunction (LV ejection fraction [LVEF] < or =35%): (1) chronic heart failure, nonsmokers, no CABG (n = 78); (2) chronic heart failure, nonsmokers, CABG (n = 46); (3) chronic heart failure, smokers, no CABG (n = 40); and (4) chronic heart failure, smokers, CABG (n = 48). Comparisons were made with age- and gender-matched patients with a history of coronary disease but no LV dysfunction or smoking history (control subjects, n = 112) and to age-predicted norms.

RESULTS

Relative to control subjects and percent-predicted values, all groups with chronic heart failure had reduced lung volumes (total lung capacity [TLC] and vital capacity [VC]) and expiratory flows (p < 0.05). CABG had no influence on lung volumes and expiratory flows in smokers, but resulted in a tendency toward a reduced TLC and VC in nonsmokers. Smokers with chronic heart failure had reduced expiratory flows compared to nonsmokers (p < 0.05), indicating an additive effect of smoking. Diffusion capacity of the lung for carbon monoxide (DLCO) was reduced in smokers and in subjects who underwent CABG, but not in patients with chronic heart failure alone. There was no relationship between LV size and pulmonary function in this population, although LV function (cardiac index and stroke volume) was weakly associated with lung volumes and DLCO.

CONCLUSIONS

We conclude that patients with chronic heart failure have primarily restrictive lung changes with smoking causing a further reduction in expiratory flows.

Exercise intolerance following heart transplantation: the role of pulmonary diffusing capacity impairment

STUDY OBJECTIVES

Although impairment of the diffusing capacity of the lung for carbon monoxide (DLCO) in heart transplant recipients is well-documented, there are limited data on its impact on exercise capacity in these patients. The aim of this study was to determine the effect of DLCO reduction on exercise capacity in heart transplant recipients.

DESIGN

Descriptive cohort study.

SETTING

A regional cardiopulmonary transplant center.

PARTICIPANTS

Twenty-six heart transplant recipients who were studied before and after transplantation compared with 26 healthy volunteers.

MEASUREMENTS

Spirometry and static lung volumes were measured using body plethysmography, DLCO was measured using the single-breath technique, and progressive cardiopulmonary exercise was performed using a bicycle ergometer, continuous transcutaneous blood gas monitoring, and on-line analysis of minute ventilation, oxygen uptake (VO(2)), and carbon dioxide production.

RESULTS

Before transplantation, the mean percent predicted for hemoglobin-corrected DLCO was reduced in patients (73.2%) compared to healthy control subjects (98.8%; p < 0.001) and declined significantly after transplantation (60.1%; p < 0.05). Although the mean maximal symptom-limited VO(2) (VO(2)max) increased after transplantation (increase, 41.3 to 48.6% of predicted; p < 0.05), it remained substantially lower than normal (92.9%; p < 0.001). There was a significant correlation between DLCO and VO(2)max after transplantation (r = 0.61; p = 0.001), but not before transplantation (r = 0.09; p = 0.66). DLCO was also inversely correlated with other respiratory responses to exercise, including the following: the ventilatory response to exercise (r = -0.44; p < 0.05); dead space to tidal volume ratio (r = -43; p < 0.05); and the alveolar-arterial oxygen gradient (r = -0. 45; p < 0.05), but there was no correlation between any of these variables and DLCO before transplantation.

CONCLUSION

DLCO reduction after heart transplantation appears to represent persistent gas exchange impairment and contributes to exercise limitation in heart transplant recipients.

Lack of improvement of lung diffusing capacity following fluid withdrawal by ultrafiltration in chronic heart failure

OBJECTIVES

We sought to investigate the possibility that lung diffusing capacity reduction observed in chronic heart failure is reversible in the short term.

BACKGROUND

Mechanical properties of the lung usually ameliorate with antifailure treatment including drugs, ultrafiltration and heart transplantation, whereas lung diffusion rarely improves.

METHODS

We studied the mechanical properties of the lung (pulmonary function tests with determination of alveolar volume, extravascular lung fluids and lung tissue), lung diffusion for carbon monoxide (DLco), including membrane diffusing capacity (Dm), pulmonary capillary blood volume (Vc) and pulmonary hemodynamics, in 28 patients with stable chronic heart failure, before a single session of extracorporeal ultrafiltration (3,973 +/- 2200 ml) and four days thereafter. Lung mechanics and diffusion were also evaluated in 18 normal subjects.

RESULTS

Vital capacity, forced expiratory volume (1 s) and maximal voluntary ventilation were lower in patients when compared with normal subjects, and increased after ultrafiltration from 2.1 +/- 0.7 to 2.5 +/- 0.7(1)*, 1.7 +/- 0.5 to 2.0 +/- 0.6(1)* and 67 +/- 25 to 79 +/- 26 (1/min)*, respectively (* p < 0.02 vs. pre-ultrafiltration). Post-ultrafiltration alveolar volume was augmented, while lung tissue, body weight (approximately 6 kg), chest X-ray extravascular lung water score and pulmonary vascular pressure were reduced. Heart dimensions (echocardiography) remained unchanged. DLco, Dm and Vc were 29.0 +/- 5.0 ml/min/mm Hg, 47.0 +/- 11.0 ml/min/mm Hg, 102 +/- 20 ml in normal subjects and 17.1 +/- 4.0#, 24.1 +/- 6.5#, 113 +/- 38 and 17.0 +/- 5.0#, 24.8 +/- 7.9#, 100 +/- 39 in patients before and after ultrafiltration, respectively (# = p < 0.01 vs. controls).

CONCLUSIONS

In chronic heart failure, ultrafiltration improves volumes and mechanical properties of the lung by reducing lung fluids. Diffusion is unaffected by ultrafiltration, suggesting that, in chronic heart failure, the alveolar-capillary membrane abnormalities are fluid-independent.

Mechanisms of pulmonary transfer factor decline following heart transplantation

OBJECTIVE

Although the decline in the pulmonary transfer factor (TL(CO)) following heart transplantation is well documented, the causes and mechanisms of this decline remain unknown. The aim of this study was to determine the relative contribution of each of TL(CO) components (the diffusing capacity of the alveolar-capillary membrane (D(M)), the pulmonary capillary blood volume (V(C)) and haemoglobin concentration) to TL(CO) reduction in heart transplant recipients.

METHODS

TL(CO) and its components were measured in 75 heart transplant recipients (mean age 48 years, range 19-61) between 6 weeks and 36 months after transplantation using the Roughton and Forster method and the single-breath technique. Results were compared with data from 38 heart transplant candidates (mean age 51 years, range 34-61) and 26 normal subjects (mean age 47 years, range 27-62).

RESULTS

The mean percentage predicted TL(CO) was reduced in recipients compared to candidates (56.9 and 69.9%, respectively, P<0. 001) and both were lower than normal controls (97.7%, P<0.001). The mean percent predicted V(C) was also reduced in recipients compared to candidates (52.8% vs. 80.2 (4.2)%, P<0.001) which was also lower than normal subjects (102%, P<0.001). D(M) was equally reduced in recipients and candidates (77.7 and 81.4%, respectively, P=0.48) compared to normal subjects (100.0%, P<0.001). Correction for haemoglobin concentration increased TL(CO) in recipients to 63.5% (P<0.001), but it remained lower than haemoglobin-corrected TL(CO) in candidates (71.1%, P<0.001). In recipients, the intra-capillary resistance (1/thetaV(C)) formed 60% of the total resistance to CO transfer (1/TL(CO)) compared to 50% in candidates and normal subjects.

CONCLUSIONS

TL(CO) decline following heart transplantation is due to an increase in the intra-capillary resistance, and this appears to be due to a combination of anaemia and reduced pulmonary capillary blood volume, with the diffusing capacity of the alveolar-capillary membrane remaining unchanged.

Ventilatory capacity and exercise tolerance in patients with chronic stable heart failure

BACKGROUND

Patients with chronic heart failure complain of breathlessness. This is associated with an increase in the ventilatory response to carbon dioxide production (VE/VCO(2) slope), yet a reduction in the maximal ventilation achieved at peak exercise. We analysed ventilatory capacity in heart failure in relation to exercise capacity.

METHODS

We analysed data from 74 patients with chronic stable heart failure [age (S.D.) 50.6 (8.8) years; left ventricular ejection fraction 30 (15)%] and 36 controls [48.9 (11.5) years]. Subjects undertook maximal incremental exercise testing with metabolic gas exchange measurements to derive peak oxygen consumption (VO(2)), the VE/VCO(2) slope and ventilation. Spirometry was used to measure FEV(1) and FVC. Maximal voluntary ventilation (MVV) was calculated as FEV(1)x 35.

RESULTS

Peak VO(2) was lower in patients [20.9 (7.5) ml min(-1) kg(-1) vs. 34.5 (10.1); P<0.001] and VE/VCO(2) greater [33.4 (10.7) vs. 26.0 (4.7); P<0.001]. Ventilation at peak exercise was lower in patients [63.5 (20.4) l/min vs. 86.9 (29.5); P<0.001], as was MVV [110.1 (37.9) l/min vs. 136.2 (53.1); P<0.001], but ventilation at peak as a proportion of MVV was the same in patients [60.0 (19.0)%] as controls [65.7 (12.4)%)]. There was an inverse relation between peak VO(2) and VE/VCO(2) slope (r=-0. 62; P<0.001). Percentage predicted FEV(1) correlated with ventilation at peak (r=0.62; P<0.001) and inversely with VE/VCO(2) slope (r=-0.32; P<0.001). There was no relation between percentage of MVV achieved and peak VO(2), or VE/VCO(2) slope.

CONCLUSIONS

Although ventilation at peak exercise is lower in patients with heart failure than normal subjects, ventilation is the same proportion of maximal voluntary ventilation. These findings suggest that ventilatory capacity does not limit exercise capacity in heart failure.

The alveolar-capillary membrane diffusing capacity and the pulmonary capillary blood volume in heart transplant candidates

OBJECTIVES

To determine the mechanism of impairment of pulmonary transfer factor for carbon monoxide (TL(CO)) in heart transplant candidates, as this is the most common lung function abnormality.

SETTING

Regional cardiopulmonary transplant centre.

METHODS

TL(CO) and its components (the diffusing capacity of the alveolar-capillary membrane (D(M)) and the pulmonary capillary blood volume (V(C))) were measured using the Roughton and Forster method and the single breath technique in 38 patients with severe chronic heart failure awaiting heart transplantation (mean age 51 years, range 19 to 61; mean left ventricular ejection fraction 12.8%). Results were compared with data from 26 normal subjects (mean age 47 years, range 27 to 62).

RESULTS

Mean per cent predicted TL(CO), D(M), and V(C) were significantly reduced in patients (69.9%, 81.4%, and 80.2% of predicted, respectively) compared with controls (97.7%, 100.1%, and 102.3% of predicted, respectively, p < 0.001). The relative contribution of the two components of TL(CO) in patients was similar to that of normal subjects, with each component accounting for approximately 50% of the total resistance to diffusion (1/TL(CO)).

CONCLUSIONS

TL(CO) impairment in patients with severe chronic heart failure awaiting heart transplantation results from a proportionate reduction in both D(M) and V(C), suggesting a significant disturbance of the pulmonary vascular bed.