Effects of lung volume reduction surgery on left ventricular diastolic filling and dimensions in patients with severe emphysema

By deflating the lungs pulmonologists help the cardiologists. A literature review

In this review, we present the effects of lung hyperinflation on the cardiovascular system (CVS) and the beneficial outcomes of different deflation treatment modalities. We discuss the effects of long-acting bronchodilator drugs, medical and surgical lung volume reduction on the performance of the CVS. Although there is a small number of studies investigating lung deflation and the CVS, the short-term improvement in heart function was clearly demonstrated. However, more studies, with longer duration, are needed to verify these significant beneficial effects of deflation of the lungs on the CVS. Dynamic hyperinflation during exercise could be a research model to investigate further the effects of lung hyperinflation and/or deflation on the CVS.

Bisoprolol versus celiprolol on dynamic hyperinflation, cardiopulmonary exercise and domiciliary safety in COPD: a single-centre, randomised, crossover study

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is frequently associated with cardiovascular disease. The utility of beta-blockers for treating patients with COPD may be beneficial, but their safety remains uncertain, including worsening of dynamic hyperinflation (DH) during exercise. We hypothesised that among cardioselective beta-blockers celiprolol, due to its partial beta-2 agonist activity, may be safer than bisoprolol on exercise DH.

METHODS

We measured isotime inspiratory capacity (IC) during cycle endurance testing in eleven moderate-severe COPD subjects, alongside other non-invasive cardiopulmonary exercise, bioreactance cardiac output, pulmonary function, biomarkers and daily domiciliary measures. Participants received titrated doses of either bisoprolol (maximim 5 mg) or celiprolol (maximum 400 mg) in randomised crossover fashion, each over 4 weeks.

RESULTS

Clinically relevant DH occurred between resting and exercise isotime IC but showed no significant difference with either beta-blocker compared with post-run-in pooled baseline or between treatments. There were no other significant differences observed for remaining exercise ventilatory; non-invasive cardiac output; resting pulmonary function; beta-2 receptor and cardiac biomarkers; domiciliary pulmonary function, oxygen saturation and symptom outcomes, either between treatments or compared with baseline. No significant adverse effects occurred.

CONCLUSIONS

Significant DH in moderate-severe COPD subjects was no different between bisoprolol or celiprolol or versus baseline. A broad spectrum of other non-invasive cardiopulmonary and domiciliary safety outcomes was equally reassuring. Bronchoprotection with a concomitant long-acting muscarinic antagonist might be an important safety measure in this context.

TRIAL REGISTRATION NUMBER

NCT02380053.

Advances in Surgical and Mechanical Management of Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD) is the third leading cause of mortality in the United States, behind cardiovascular and malignant disorders. As the understanding of the pathogenesis has evolved, it led to targeting mechanical aspects of the disease to improve patient symptoms and quality of life. Modern management of COPD offers a variety of mechanical and surgical treatments for patients with advanced disease who do not achieve benefit from medical therapy alone. These treatments include therapies aimed at lung volume reduction, through surgical or bronchoscopic techniques. While these techniques are established and have proven benefit, others are still under development. Herein we discuss these techniques, aimed at improving clinician recognition of patients that may benefit from these interventions.

Reduction of Lung Hyperinflation Improves Cardiac Preload, Contractility, and Output in Emphysema: A Prospective Cardiac Magnetic Resonance Study in Patients Who Received Endobronchial Valves

RATIONALE

Pulmonary hyperinflation in patients with Chronic Obstructive Pulmonary Disease (COPD) has been related to smaller cardiac chamber sizes and impaired cardiac function. Nowadays, bronchoscopic lung volume reduction (BLVR) with endobronchial valves is a treatment option to reduce pulmonary hyperinflation in patients with severe emphysema.

OBJECTIVES

We hypothesized that reduction of hyperinflation would improve cardiac preload in this patient group. In addition, we investigated whether the treatment would result in elevated pulmonary artery pressures due to pulmonary vascular bed reduction.

METHODS

We included patients with emphysema and severe hyperinflation (defined by a baseline residual volume >175% of predicted) who were eligible for BLVR with endobronchial valves. Cardiac magnetic resonance imaging was obtained one day prior to treatment and at eight week follow-up. Primary endpoint was cardiac preload, as measured by the right ventricle end-diastolic volume index (RVEDVI). As secondary endpoints, we measured indexed end-diastolic and end-systolic volumes of the right ventricle, left atrium, and left ventricle, pulmonary artery pressures, cardiac output, ejection fraction, and strain.

MEASUREMENTS AND MAIN RESULTS

Twenty-four patients were included. At eight week follow-up, RVEDVI was significantly improved (+7.9 ml/m2, SD 10.0, p=0.001). In addition to increased stroke volumes, we found significantly higher ejection fractions and strain measurements. Although cardiac output was significantly increased (+0.9L/min, SD 1.5, p=0.007), there were no changes in pulmonary artery pressures.

CONCLUSIONS

We found that reduction of hyperinflation using BLVR with endobronchial valves significantly improved cardiac preload, myocardial contractility, and cardiac output, without changes in pulmonary artery pressures. Clinical trial registered with ClinicalTrials.gov (NCT03474471).

Impaired Spontaneous Baroreceptor Reflex Sensitivity in Patients With COPD Compared to Healthy Controls: The Role of Lung Hyperinflation

Background and Objectives: Patients with chronic obstructive pulmonary disease (COPD) are at increased risk for cardiovascular disease. This study aimed to investigate the relationship between pulmonary hyperinflation and baroreceptor reflex sensitivity (BRS), a surrogate for cardiovascular risk. Methods: 33 patients with COPD, free from clinical cardiovascular disease, and 12 healthy controls were studied. Participants underwent pulmonary function and non-invasive hemodynamic measurements. BRS was evaluated using the sequence method during resting conditions and mental arithmetic stress testing. Results: Patients with COPD had evidence of airflow obstruction [forced expiratory volume in 1 s predicted (FEV₁%) 26.5 (23.3-29.1) vs. 91.5 (82.8-100.8); P < 0.001; geometric means (GM) with 95% confidence interval (CI)] and lung hyperinflation [residual volume/total lung capacity (RV/TLC) 67.7 (64.3-71.3) vs. 41.0 (38.8-44.3); P < 0.001; GM with 95% CI] compared to controls. Spontaneous mean BRS (BRSmean) was significantly lower in COPD, both during rest [5.6 (4.2-6.9) vs. 12.0 (9.1-17.6); P = 0.003; GM with 95% CI] and stress testing [4.4 (3.7-5.3) vs. 9.6 (7.7-12.2); P < 0.001; GM with 95% CI]. Stroke volume (SV) was significantly lower in the patient group [-21.0 ml (-29.4 to -12.6); P < 0.001; difference of the means with 95% CI]. RV/TLC was found to be a predictor of BRS and SV (P < 0.05 for both), independent of resting heart rate. Conclusion: We herewith provide evidence of impaired BRS in patients with COPD. Hyperinflation may influence BRS through alteration of mechanosensitive vagal nerve activity.

Critical Analysis of the National Emphysema Treatment Trial Results for Lung-Volume-Reduction Surgery

The National Emphysema Treatment Trial compared medical treatment of severe pulmonary emphysema with lung-volume-reduction surgery in a multiinstitutional randomized prospective fashion. Two decades later, this trial remains one of the key sources of information we have on the treatment of advanced emphysematous lung disease. The trial demonstrated the short- and long-term effectiveness of surgical intervention as well as the need for strict patient selection and preoperative workup. Despite these findings, the key failure of the trial was an inability to convince the medical community of the value of surgical resection in the treatment of advanced emphysema.

The Effects of Endobronchial Coil Therapy on Right Ventricular Functions

Lung hyperinflation is an important therapeutic target in symptomatic emphysema patients. Endobronchial therapies that reduce end-expiratory lung volume are increasingly being used in advanced cases. However, there is paucity of data regarding the effects of these therapies on the heart functions. The aim of this study is to evaluate the right ventricular functions before and after the procedure in patients who underwent endobronchial coil therapy (EBCT).Patients who were between 18 and 80 years of age and scheduled for EBCT with GOLD 3-4 were enrolled in the study. Right heart functions were evaluated using MPI, TAS, TAPSE. Right atrium area and maximum velocity of tricuspid regurgitation were also noted.A total of 23 patients were enrolled in the study. 21 patients underwent bilateral intervention, while only 2 patients received unilateral treatment. There was an improvement in MPI (0.49 ± 0.15 vs 0.39 ± 0.11, p < 0.001) and TAS (11.6 (9 - 15) vs 13.2 (9.80 - 17.0), p = 0.001). Peak TRV (2.52 ± 0.6, 2.38 ± 0.6, p = 0.02) and PASP values were lower in the post-operative period (41.15 ± 5.94 vs 36.83 ± 8.01 p = 0.019).In this current study, we found improved echocardiographic RtV parameters in patients who received EBCT treatment.

Respiratory function, autonomic dysfunction, and systemic inflammation are closely linked in patients with COPD and tidal flow limitation: An exploratory study

RATIONALE

The study aimed to investigate the interplay among respiratory function, autonomic dysfunction, and systemic inflammation in COPD patients.

METHODS

In 19 COPD patients, functional respiratory parameters, heart rate variability (HRV), and plasma high-sensitivity-C-reactive-protein (hs-CRP) were assessed. Forced oscillation technique (FOT) was used to detect the absence (NFL) or presence (FL) of resting tidal expiratory flow limitation. Subsequently, patients underwent an incremental shuttle walking test (ISWT). Twenty healthy subjects were also shown as controls.

RESULTS

FEV₁, DL_CO, and lung volumes displayed significant correlations with LH/FH ratio (0.56 < r²<0.27,p < 0.01). A significant relationship was found between LH/FH ratio with IC/TLC ratio% (r² = 0.29,p < 0.05) and hs-CRP (r² = 0.26,p < 0.05). Patients with FL had greater hs-CRP plasma levels (p < 0.05), lower IC/TLC% (p < 0.05), and higher LH/FH ratio (p<0.001).

CONCLUSIONS

Worse airflow obstruction was associated with a higher LH/HF ratio, directly related, to hs-CRP and indices of dynamic hyperinflation. The presence of resting tidal FL with dynamic pulmonary hyperinflation is a strong driver of systemic inflammation and autonomic dysfunction.

Surgical Therapies for Chronic Obstructive Pulmonary Disease

Patients with severe chronic obstructive pulmonary disease who fail maximal medical therapy and bronchoscopic interventions have surgical options to improve lung function, quality of life, and exercise performance. Carefully selected patients with upper lobe predominant emphysema can consider lung volume reduction surgery. Patients with upper lobe-predominant emphysema and low exercise performance have a survival advantage. Patients with large bulla compressing adjacent lung tissue occupying more than one-third of the lung benefit from bullectomy. Patients with advanced chronic obstructive pulmonary disease ineligible for or failing other surgical or bronchoscopic interventions can consider lung transplantation if free from major comorbidities.

Emerging Interventional Pulmonary Therapies for Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease is a condition characterized by progressive airflow limitation caused by airway and parenchymal inflammation. Current medical therapies, including bronchodilators, corticosteroids, and anti-inflammatory medications, have been shown to variably improve pulmonary function or quality of life without providing a long-term mortality benefit. Mortality benefits to therapy have been demonstrated in only 2 therapeutic interventions to date: long-term use of daily supplemental oxygen and surgical lung volume reduction (LVRS) for upper-lobe-predominant disease in patients with a low baseline exercise capacity. Newer bronchoscopic techniques for lung volume reduction (bLVR) have attracted interest from clinicians and researchers. To achieve successful results, these advanced therapies require an interdisciplinary approach between general and interventional pulmonologists and thoracic radiologists. In this article, we aim to review the latest interventional pulmonary techniques for treatment of chronic obstructive pulmonary disease with an emphasis on bLVR. We will review the bLVR preprocedure imaging evaluation, postprocedure imaging findings, and explore the potential benefits and risks of therapy based on the most recent clinical trial evidence.

Cigarette Smoke Exposure and Radiographic Pulmonary Vascular Morphology in the Framingham Heart Study

Rationale: Cigarette smoke exposure is a risk factor for many lung diseases, and histologic studies suggest that tobacco-related vasoconstriction and vessel loss plays a role in the development of emphysema. However, it remains unclear how tobacco affects the pulmonary vasculature in general populations with a typical range of tobacco exposure, and whether these changes are detectable by radiographic methods. Objectives: To determine whether tobacco exposure in a generally healthy population manifests as lower pulmonary blood vessel volumes and vascular pruning on imaging. Methods: A total of 2,410 Framingham Heart Study participants with demographic data and smoking history underwent volumetric whole-lung computed tomography from 2008 to 2011. Automated algorithms calculated the total blood volume of all intrapulmonary vessels (TBV), smaller peripheral vessels (defined as cross-sectional area <5 mm² [BV5]), and the relative fraction of small vessels (BV5/TBV). Tobacco exposure was assessed as smoking status, cumulative pack-years, and second-hand exposure. We constructed multivariable linear regression models to evaluate associations of cigarette exposure and pulmonary blood vessel volume measures, adjusting for demographic covariates, including age, sex, height, weight, education, occupation, and median neighborhood income. Results: All metrics of tobacco exposure (including smoking status, pack-years, and second-hand exposure) were consistently associated with higher absolute pulmonary blood vessel volume, higher small vessel volume, and/or higher small vessel fraction. For example, ever-smokers had a 4.6 ml higher TBV (95% confidence interval [CI] = 2.9-6.3, P < 0.001), 2.1 ml higher BV5 (95% CI = 1.3-2.9, P < 0.001), and 0.28 percentage-point-higher BV5/TBV (95% CI = 0.03-0.52, P = 0.03) compared with never-smokers. These associations remained significant after adjustment for percent predicted forced expiratory volume in 1 second, cardiovascular comorbidities, and did not differ based on presence or absence of airflow obstruction. Conclusions: Using computed tomographic imaging, we found that cigarette exposure was associated with higher pulmonary blood vessel volumes, especially in the smaller peripheral vessels. Although, histologically, tobacco-related vasculopathy is characterized by vessel narrowing and loss, our results suggest that radiographic vascular pruning may not be a surrogate of these pathologic changes.

Cardio-Pulmonary Changes After Bronchoscopic Lung Volume Reduction with Endobronchial One-Way Valves

INTRODUCTION

To evaluate the cardio-pulmonary hemodynamics changes before and after valve treatment, and their correlation with lobe volume reduction.

METHODS

This retrospective multicentre study included consecutive patients undergoing bronchoscopic valve treatment for heterogeneous emphysema. In addition to standard functional evaluation, patients underwent cardiac evaluation by Doppler trans-thoracic echocardiography. The difference in respiratory and cardio-pulmonary hemodynamics indexes before and 3-month after the procedure, and their relationship with changes in lobar volume were evaluated.

RESULTS

Seventy-seven patients were included in the study; of these 13 (17%) presented pulmonary hypertension. Only patients with target lobar volume reduction ≥ 563 mL (n = 50) presented a significant improvement of forced expiratory volume in one second, residual volume, 6 min-walk test, and St. George's Respiratory Questionnaire score; a significant reduction of pulmonary artery pressure, and an improvement of left and right ventricle end-systolic volume; of left and right ventricle end-diastolic volume, and of left and right ventricle stroke volume. The change in residual volume was significantly correlated with changes in forced expiratory volume in one second (r = 0.68; p < 0.001); in 6 min-walk test (r = 0.71; p < 0.001); in St. George's Respiratory Questionnaire (r = 0.54; p < 0.001); in pulmonary artery pressure (r = 0.39; p = 0.001), in left (r = 0.28; p = 0.01) and right (r = 0.33; p = 0.002) ventricle end-systolic volume, in left (r =  - 0.29; p = 0.008) and right (r =  - 0.34; p = 0.007) end-diastolic volume, and in left (r =  - 0.76; p = 0.009) and right (r =  - 0.718; p = 0.001) ventricle stroke volume.

CONCLUSION

Bronchoscopic valve treatment seemed to have positive effects on cardio-pulmonary hemodynamics, and these changes were correlated with reductions of lobar volume.

Pulmonary hypertension in chronic obstructive pulmonary disease and emphysema patients: prevalence, therapeutic options and pulmonary circulatory effects of lung volume reduction surgery

The exact prevalence of pulmonary hypertension (PH) and cor pulmonale (CP) in chronic obstructive pulmonary disease (COPD) is unknown, and varies considerably from 20-91%. Usually, mean pulmonary artery pressure (mPAP) does not exceed 30 mmHg, and PH is not severe. However, PH and CP are important predictors of mortality in COPD and contribute to disability in this disease. Many factors contribute to the development of PH in chronic lung disease, including reduction of the pulmonary vascular cross-sectional area due to parenchymal loss and accompanying hypoxia, effects of abnormal pulmonary mechanics due to hyperinflation, but also vascular remodeling processes. So far, PH associated with chronic lung disease cannot be treated medically. Therefore, it is indicated to treat the underlying pulmonary disease. Patients with severe PH should be referred to centers experienced in the management of PH and enrollment in clinical trials should be considered. Lung volume reduction surgery (LVRS) theoretically further increases pulmonary vascular resistance (PVR) by reducing the vascular bed when resecting lung tissue, however, this might be compensated by better pulmonary mechanics through reduction of hyperinflation, which will be discussed in the present article.

Lung volume reduction surgery or bronchoscopic lung volume reduction: is there an algorithm for allocation?

Chronic obstructive pulmonary disease (COPD) is the fourth leading cause of death in the world with the annual number of deaths increasing every year. Alterations in chest wall mechanics, respiratory muscle mechanics, and impaired cardiac function that result from increased air-trapping are well known sequelae of COPD and contribute to increased morbidity and mortality. A reduction in hyperinflation can improve cardiopulmonary function. In selected patients with COPD and an emphysema phenotype, lung volume reduction surgery (LVRS) has demonstrated improvements in symptom burden and mortality. Minimally invasive bronchoscopic techniques that reduce end-expiratory lung volume have shown improvements in lung function, dyspnea and quality of life. In this review, we review selection criteria, risks, and benefits of surgical and bronchoscopic lung volume reduction (BLVR). Recommendations are provided to guide treatment decisions based on the current literature.

Valve therapy in patients with emphysematous type of chronic obstructive pulmonary disease (COPD): from randomized trials to patient selection in clinical practice

In recent years a number of endoscopic methods have emerged to treat patients with severe emphysematous type of chronic obstructive pulmonary disease (COPD), who are primarily symptomatic due to hyperinflation despite optimal medical management. Of these techniques, implantation of endobronchial one-way valves into targeted airways of isolated emphysematous lobes appears to be one of the most promising innovations. Results from randomized controlled trials of valve therapy for emphysema show consistent benefits in terms of lung function, exercise capacity, symptoms, and quality of life. This review aims to provide a comprehensive summary of the currently available scientific data, discussion of typical treatment related side effects, and recommendations for patient selection in clinical practice.

RECENT ASPECTS OF CARDIAC REMODELING IN PATIENTS WITH CHRONIC OBSTRUCTIVE PULMONARY DISEASE

The paper aimed to present evidence of the effect of some pathophysiological features of chronic obstructive pulmonary disease (COPD) on cardiac remodeling in patients free of overt cardiovascular diseases, traditional cardiovascular risk factors and pulmonary hypertension. Contrary to traditional beliefs that cardiac abnormalities in COPD have been mainly associated with the right ventricle, several recent studies have shown an independent effect of pulmonary hyperinflation and emphysema on left ventricular (LV) diastolic filling and LV hypertrophy. Pulmonary hyperinflation and emphysema cause intrathoracic hypovolemia, low preload, small end-diastolic dimension and mechanical compression of LV chamber which could worsen end-diastolic stiffness. Interestingly, that the presence of LV hypertrophy in COPD patients is important but currently poorly understood area of investigation. Pulmonary hyperinflation, increased arterial stiffness and sympathetic activation may be associated with LV hypertrophy. Two-dimensional ultrasound speckle tracking studies have shown the presence of sub-clinical LV systolic dysfunction in patients even with moderate COPD and free of overt cardiovascular diseases. Sarcopenia related to the inflammatory-catabolic state in COPD and hypoxia could play an important role regarding LV systolic dysfunction. Recent data reported the effects of long-acting bronchodilators on reducing lung hyperinflation (inducing lung deflation). Further studies are required to evaluate the effects of pharmacological lung deflation therapy on cardiac volume and function.

The Link between Reduced Inspiratory Capacity and Exercise Intolerance in Chronic Obstructive Pulmonary Disease

Low inspiratory capacity (IC), chronic dyspnea, and reduced exercise capacity are inextricably linked and are independent predictors of increased mortality in chronic obstructive pulmonary disease. It is no surprise, therefore, that a major goal of management is to improve IC by reducing lung hyperinflation to improve respiratory symptoms and health-related quality of life. The negative effects of lung hyperinflation on respiratory muscle and cardiocirculatory function during exercise are now well established. Moreover, there is growing appreciation that a key mechanism of exertional dyspnea in chronic obstructive pulmonary disease is critical mechanical constraints on tidal volume expansion during exercise when resting IC is reduced. Further evidence for the importance of lung hyperinflation comes from multiple studies, which have reported the clinical benefits of therapeutic interventions that reduce lung hyperinflation and increase IC. A reduced IC in obstructive pulmonary disease is further eroded by exercise and contributes to ventilatory limitation and dyspnea. It is an important outcome for both clinical and research studies.

Left ventricular end-diastolic volume predicts exercise capacity in patients with a normal ejection fraction

BACKGROUND

Exercise capacity is a powerful predictor of all-cause mortality. The duration of exercise with treadmill stress testing is an important prognostic marker in both healthy subjects and patients with cardiovascular disease. Left ventricular (LV) structure is known to adapt to sustained changes in level of physical activity.

HYPOTHESIS

Poor exercise capacity in patients with a preserved LV ejection fraction (LVEF) should be reflected in smaller LV dimensions, and a normal exercise capacity should be associated with larger LV dimensions, irrespective of comorbidities.

METHODS

This hypothesis was first tested in a cross-sectional analysis of 201 patients with normal chamber dimensions and preserved LVEF who underwent a clinically indicated treadmill stress echocardiogram using the Bruce protocol (derivation cohort). The best LV dimensional predictor of exercise capacity was then tested in 1285 patients who had a Bruce-protocol treadmill exercise stress test and a separate transthoracic echocardiogram (validation cohort).

RESULTS

In the derivation cohort, there was a strong positive relationship between exercise duration and LV end-diastolic volume deciles (r ²  = 0.85; P < 0.001). Regression analyses of several LV dimensional parameters revealed that the body surface area-based LV end-diastolic volume index was best suited to predict exercise capacity (P < 0.0001). In a large validation cohort, LV end-diastolic volume was confirmed to predict exercise capacity (P < 0.0001).

CONCLUSIONS

Among patients referred for outpatient stress echocardiography who have a preserved LVEF and no evidence of myocardial ischemia, we found a strong positive association between LV volume and exercise capacity.

Endobronchial Coils Versus Lung Volume Reduction Surgery or Medical Therapy for Treatment of Advanced Homogenous Emphysema

Rationale: Bronchoscopic lung volume reduction utilizing shape-memory nitinol endobronchial coils (EBC) may be safer and more effective in severely hyperinflated homogeneous emphysema compared to medical therapy or lung volume reduction surgery (LVRS). Methods: The effect of bilateral EBC in patients with homogeneous emphysema on spirometry, lung volumes and survival was compared to patients with homogeneous emphysema randomized in the National Emphysema Treatment Trial (NETT) to LVRS or medical therapy. NETT participants were selected to match EBC participants in age, baseline spirometry, and gender. Outcomes were compared from baseline, at 6 and 12 months. Results: There were no significant baseline differences in gender in the EBC, NETT-LVRS or medical treatment patients. At baseline no differences existed between EBC and NETT-LVRS patients in forced expiratory volume in 1 second ( FEV₁) or total lung capacity (TLC) %-predicted; residual volume (RV) and diffusing capacity of the lung for carbon monoxide (DLco) %-predicted were higher in the EBC group compared to NETT-LVRS (p < 0.001). Compared to the medical treatment group, EBC produced greater improvements in FEV₁ and RV but not TLC at 6 months. FEV₁ and RV in the EBC group remained significantly improved at 12-months compared to the medical treatment group. While all 3 therapies improved quality of life, survival at 12 months with EBC or medical therapy was greater than NETT-LVRS. Conclusion: EBC may be a potential therapeutic option in patients with severe homogeneous emphysema and hyperinflation who are already receiving optimal medical treatment.

Effect of lung deflation with indacaterol plus glycopyrronium on ventricular filling in patients with hyperinflation and COPD (CLAIM): a double-blind, randomised, crossover, placebo-controlled, single-centre trial

BACKGROUND

Pulmonary hyperinflation in chronic obstructive pulmonary disease (COPD) is associated with reduced biventricular end-diastolic volumes and increased morbidity and mortality. The combination of a long-acting β agonist (LABA) and a muscarinic antagonist (LAMA) is more effective in reducing hyperinflation than LABA-inhaled corticosteroid combination therapy but whether dual bronchodilation improves cardiac function is unknown.

METHODS

We did a double-blind, randomised, two-period crossover, placebo-controlled, single-centre study (CLAIM) at the Fraunhofer Institute of Toxicology and Experimental Medicine (Hannover, Germany), a specialty clinic. Eligible participants were patients aged at least 40 years with COPD, pulmonary hyperinflation (defined by a baseline residual volume >135% of predicted), a smoking history of at least ten pack-years, and airflow limitation (FEV₁ <80% predicted and post-bronchodilator FEV₁: forced vital capacity <0·7). Patients with stable cardiovascular disease were eligible, but those with arrhythmias, heart failure, unstable ischaemic heart disease, or uncontrolled hypertension were not. We randomly assigned participants (1:1) to either receive a combined inhaled dual bronchodilator containing the LABA indacaterol (110 μg as maleate salt) plus the LAMA glycopyrronium (50 μg as bromide salt) once per day for 14 days, followed by a 14-day washout, then a matched placebo for 14 days, or to receive the same treatments in reverse order. The randomisation was done using lists and was concealed from patients and investigators. The primary endpoint was the effect of indacaterol-glycopyrronium versus placebo on left-ventricular end-diastolic volume measured by MRI done on day 1 (visit 4) and day 15 (visit 5) in treatment period 1 and on day 29 (visit 6) and day 43 (visit 7) in treatment period 2 in the per-protocol population. Left-ventricular end-diastolic volume was indexed to body surface area. Safety was assessed in all participants who received at least one dose of the study drug. This study is registered with ClinicalTrials.gov, number NCT02442206.

FINDINGS

Between May 18, 2015, and April 20, 2017, we randomly assigned 62 eligible participants to treatment; 30 to indacaterol-glycopyrronium followed by placebo and 32 to placebo followed by indacaterol-glycopyrronium. The 62 randomly assigned patients were included in the intent-to-treat analysis. There were two protocol violations and therefore 60 were included in the per-protocol analysis. 57 patients completed both treatment periods. After indacaterol-glycopyrronium treatment, left-ventricular end-diastolic volume increased from a mean 55·46 mL/m² (SD 15·89) at baseline to a least-squares (LS) mean of 61·76 mL/m² (95% CI 57·68-65·84), compared with a change from 56·42 mL/m² at baseline (13·54) to 56·53 mL/m² (52·43-60·62) after placebo (LS means treatment difference 5·23 mL/m² [95% CI 3·22 to 7·25; p<0·0001]). The most common adverse events reported with indacaterol-glycopyrronium were cough (in nine patients [15%] of 59) and throat irritation (in seven [12%]). With placebo, the most common adverse events reported were headache (in five patients [8%] of 61) and upper respiratory tract infection (in four [7%]). Two patients had serious adverse events: one (2%) after indacaterol-glycopyrronium (endometrial cancer) and one (2%) after placebo (myocardial infarction); these were not thought to be treatment related. No patients died during the study.

INTERPRETATION

This is the first study to analyse the effect of LABA-LAMA combination therapy on cardiac function in patients with COPD and lung hyperinflation. Dual bronchodilation with indacaterol-glycopyrronium significantly improved cardiac function as measured by left-ventricular end-diastolic volume. The results are important because of the known association of cardiovascular impairment with COPD, and support the early use of dual bronchodilation in patients with COPD who show signs of pulmonary hyperinflation.

FUNDING

Novartis Pharma GmbH.

Airway obstruction and lung hyperinflation in COPD are linked to an impaired left ventricular diastolic filling

AIMS

Chronic obstructive pulmonary disease (COPD) and cardiovascular diseases are thought to be linked through various factors. We aimed to assess the relationship between airway obstruction, lung hyperinflation and diastolic filling in COPD.

METHODS

The study population was a subset of the COPD cohort COSYCONET. Echocardiographic parameters included the left atrial diameter (LA), early (E) and late (A) transmitral flow, mitral annulus velocity (e'), E wave deceleration time (E[dt]), and isovolumic relaxation time (IVRT). We quantified the effect of various predictors including forced expiratory volume in 1 s (FEV₁) and intrathoracic gas volume (ITGV) on the echocardiographic parameters by multiple linear regression and integrated the relationships into a path analysis model.

RESULTS

A total of 615 COPD patients were included (mean FEV₁ 52.6% predicted). In addition to influences of age, BMI and blood pressure, ITGV was positively related to e'-septal and negatively to LA, FEV₁ positively to E(dt) (p < 0.05 each). The effect of predictors was most pronounced for LA, e'-septal and E(dt), and less for E/A, IVRT and E/e'. Path analysis was used to take into account the additional relationships between the echocardiographic parameters themselves, demonstrating that their associations with the predictors were maintained and robust.

CONCLUSIONS

Airway obstruction and lung hyperinflation were significantly associated with cardiac diastolic filling in patients with COPD, suggesting a decreased preload rather than an inherently impaired myocardial relaxation itself. This suggests that a reduction in obstruction and hyperinflation could help to improve cardiac filling.

Hyperinflated lungs compress the heart during expiration in COPD patients: a new finding on dynamic-ventilation computed tomography

Purpose

The aims of this study were to evaluate dynamic changes in heart size during the respiratory cycle using four-dimensional computed tomography (CT) and to understand the relationship of these changes to airflow limitation in smokers.

Materials and methods

A total of 31 smokers, including 13 with COPD, underwent four-dimensional dynamic-ventilation CT during regular breathing. CT data were continuously reconstructed every 0.5 s, including maximum cross-sectional area (CSA) of the heart and mean lung density (MLD). Concordance between the cardiac CSA and MLD time curves was expressed by cross-correlation coefficients. The CT-based cardiothoracic ratio at inspiration and expiration was also calculated. Comparisons of the CT indices between COPD patients and non-COPD smokers were made using the Mann–Whitney test. Spearman rank correlation analysis was used to evaluate associations between CT indices and the forced expiratory volume in 1 s (FEV_1.0) relative to the forced vital capacity (FVC).

Results

Cardiac CSA at both inspiration and expiration was significantly smaller in COPD patients than in non-COPD smokers (P<0.05). The cross-correlation coefficient between cardiac CSA and MLD during expiration significantly correlated with FEV_1.0/FVC (ρ=0.63, P<0.001), suggesting that heart size decreases during expiration in COPD patients. The change in the cardiothoracic ratio between inspiration and expiration frames was significantly smaller in COPD patients than in non-COPD smokers (P<0.01).

Conclusion

Patients with COPD have smaller heart size on dynamic-ventilation CT than non-COPD smokers and have abnormal cardiac compression during expiration.

Diastolic Dysfunction Increases the Risk of Primary Graft Dysfunction after Lung Transplant

RATIONALE

Primary graft dysfunction (PGD) is a significant cause of early morbidity and mortality after lung transplant and is characterized by severe hypoxemia and infiltrates in the allograft. The pathogenesis of PGD involves ischemia-reperfusion injury. However, subclinical increases in pulmonary venous pressure due to left ventricular diastolic dysfunction may contribute by exacerbating capillary leak.

OBJECTIVES

To determine whether a higher ratio of early mitral inflow velocity (E) to early diastolic mitral annular velocity (é), indicative of worse left ventricular diastolic function, is associated with a higher risk of PGD.

METHODS

We performed a retrospective cohort study of patients in the Lung Transplant Outcomes Group who underwent bilateral lung transplant at our institution between 2004 and 2014 for interstitial lung disease, chronic obstructive pulmonary disease, or pulmonary arterial hypertension. Transthoracic echocardiograms obtained during evaluation for transplant listing were analyzed for E/é and other measures of diastolic function. PGD was defined as PaO2/FiO2 less than or equal to 200 with allograft infiltrates at 48 or 72 hours after reperfusion. The association between E/é and PGD was assessed with multivariable logistic regression.

MEASUREMENTS AND MAIN RESULTS

After adjustment for recipient age, body mass index, mean pulmonary arterial pressure, and pretransplant diagnosis, higher E/é and E/é greater than 8 were associated with an increased risk of PGD (E/é odds ratio, 1.93; 95% confidence interval, 1.02-3.64; P = 0.04; E/é >8 odds ratio, 5.29; 95% confidence interval, 1.40-20.01; P = 0.01).

CONCLUSIONS

Differences in left ventricular diastolic function may contribute to the development of PGD. Future trials are needed to determine whether optimization of left ventricular diastolic function reduces the risk of PGD.

Left ventricular diastolic dysfunction in patients with chronic obstructive pulmonary disease: Impact of methods of assessment

BACKGROUND

The prevalence of left ventricular (LV) diastolic dysfunction in patients with chronic obstructive pulmonary disease (COPD), using different echocardiographic parameters, varies widely in the literature. The highest prevalence of LV diastolic dysfunction was detected using the mitral inflow indexes that are commonly altered in these patients due to the associated tachycardia, reduced preload, and ventricular septal shift. In this study, we aimed at evaluating the impact of the used echocardiographic method of assessment on the prevalence of LV diastolic dysfunction in patients with COPD and normal LV systolic function.

METHODS

We studied 35 patients with COPD and 18 age-matched controls. A comprehensive approach to diagnose and grade the LV diastolic dysfunction was performed in accordance with the recommendations of the American Society of Echocardiography published in 2009. The results were compared with those of mitral inflow indexes.

RESULTS

LV diastolic dysfunction was reported in 20 patients using the mitral inflow indexes while in only 12 patients using the comprehensive approach (P=.021). Compared to the controls, LV diastolic dysfunction was significantly more common in patients using the mitral inflow indexes (P=.001), while no statistically significant difference was detected between both groups using the comprehensive approach (P=.1).

CONCLUSION

The prevalence of LV diastolic dysfunction in patients with COPD varies according to the used echocardiographic approach. Further studies are recommended to determine which approach is the most accurate in estimating the true prevalence of LV diastolic dysfunction among this group of patients.

Heart Failure Impairs Muscle Blood Flow and Endurance Exercise Tolerance in COPD

Heart failure, a prevalent and disabling co-morbidity of COPD, may impair cardiac output and muscle blood flow thereby contributing to exercise intolerance. To investigate the role of impaired central and peripheral hemodynamics in limiting exercise tolerance in COPD-heart failure overlap, cycle ergometer exercise tests at 20% and 80% peak work rate were performed by overlap (FEV1 = 56.9 ± 15.9% predicted, ejection fraction = 32.5 ± 6.9%; N = 16), FEV1-matched COPD (N = 16), ejection fraction-matched heart failure patients (N = 15) and controls (N = 12). Differences (Δ) in cardiac output (impedance cardiography) and vastus lateralis blood flow (indocyanine green) and deoxygenation (near-infrared spectroscopy) between work rates were expressed relative to concurrent changes in muscle metabolic demands (ΔO2 uptake). Overlap patients had approximately 30% lower endurance exercise tolerance than COPD and heart failure (p < 0.05). ΔBlood flow was closely proportional to Δcardiac output in all groups (r = 0.89-0.98; p < 0.01). Overlap showed the largest impairments in Δcardiac output/ΔO2 uptake and Δblood flow/ΔO2 uptake (p < 0.05). Systemic arterial oxygenation, however, was preserved in overlap compared to COPD. Blunted limb perfusion was related to greater muscle deoxygenation and lactate concentration in overlap (r = 0.78 and r = 0.73, respectively; p < 0.05). ΔBlood flow/ΔO2 uptake was related to time to exercise intolerance only in overlap and heart failure (p < 0.01). In conclusion, COPD and heart failure add to decrease exercising cardiac output and skeletal muscle perfusion to a greater extent than that expected by heart failure alone. Treatment strategies that increase muscle O2 delivery and/or decrease O2 demand may be particularly helpful to improve exercise tolerance in COPD patients presenting heart failure as co-morbidity.

Effective Bronchoscopic Lung Volume Reduction Accelerates Exercise Oxygen Uptake Kinetics in Emphysema

BACKGROUND

The impact of bronchoscopic lung volume reduction (BLVR) on physiologic responses to exercise in patients with advanced emphysema remains incompletely understood. We hypothesized that effective BLVR (e-BLVR), defined as a reduction in residual volume > 350 mL, would improve cardiovascular responses to exercise and accelerate oxygen uptake (Vo₂) kinetics.

METHODS

Thirty-one patients (FEV1, 36% ± 9% predicted; residual volume, 219% ± 57% predicted) underwent a constant intensity exercise test at 70% peak work rate to the limit of tolerance before and after treatment bronchoscopy (n = 24) or sham bronchoscopy (n = 7). Physiologic responses in patients who had e-BLVR (n = 16) were compared with control subjects (ineffective BLVR or sham bronchoscopy; n = 15).

RESULTS

e-BLVR reduced residual volume (-1.1 ± 0.5 L, P = .001), improved lung diffusing capacity by 12% ± 13% (P = .001), and increased exercise tolerance by 181 ± 214 s (P = .004). Vo₂ kinetics were accelerated in the e-BLVR group but remained unchanged in control subjects (Δ mean response time, -20% ± 29% vs 1% ± 25%, P = .04). Acceleration of Vo₂ kinetics was associated with reductions in heart rate and oxygen pulse response half-times by 8% (84 ± 14 to 76 ± 15 s, P = .04) and 20% (49 ± 16 to 34 ± 16 s, P = .01), respectively. There were also increases in heart rate and oxygen pulse amplitudes during the cardiodynamic phase post e-BLVR. Faster Vo₂ kinetics in the e-BLVR group were significantly correlated with reductions in residual volume (r = 0.66, P = .005) and improvements in inspiratory reserve volume (r = 0.56, P = .024) and exercise tolerance (r = 0.63, P = .008).

CONCLUSIONS

Lung deflation induced by e-BLVR accelerated exercise Vo₂ kinetics in patients with emphysema. This beneficial effect appears to be related mechanistically to an enhanced cardiovascular response to exercise, which may contribute to improved functional capacity.

The complex care of severe emphysema: role of awake lung volume reduction surgery

The resectional lung volume reduction surgery (LVRS) procedure entailing nonanatomic resection of destroyed lung regions through general anesthesia with single-lung ventilation has shown to offer significant and long-lasting improvements in respiratory function, exercise capacity, quality of life and survival, particularly in patients with upper-lobe predominant emphysema and low exercise capacity. However mortality and morbidity rates as high as 5% and 59%, respectively, have led to a progressive underuse and have stimulated investigation towards less invasive surgical and bronchoscopic nonresectional methods that could assure equivalent clinical results with less morbidity. We have developed an original nonresectional LVRS method, which entails plication of the most severely emphysematous target areas performed in awake patients through thoracic epidural anesthesia (TEA). Clinical results of this ultra-minimally invasive procedure have been highly encouraging and in a uni-center randomized study, intermediate-term outcomes paralleled those of resectional LVRS with shorter hospital stay and fewer side-effects. In this review article we analyze indications, technical details and results of awake LVRS taking into consideration the available data from the literature.

Relationship of exercise capacity and left ventricular dimensions in patients with a normal ejection fraction. An exploratory study

OBJECTIVES

Extreme endurance exercise is known to be associated with an enlargement of the left ventricular (LV) chamber, whereas inactivity results in inverse changes. It is unknown if these dimensional relationships exist in patients.

METHODS

We analyzed the relationship of exercise capacity and LV dimension in a cohort of sequential patients with a normal ejection fraction undergoing stress echocardiography. In a total of 137 studies the following questions were addressed: (a) is there a difference in LV dimensions of patients with an excellent exercise capacity versus patients with a poor exercise capacity, (b) how is LV dimension and exercise capacity affected by LV wall thickness and (c) how do LV dimensions of patients who are unable to walk on a treadmill compare to the above groups.

RESULTS

Patients with a poor exercise capacity or who are unable to physically exercise have a 34 percent smaller LV cavity size when compared to patients with an excellent exercise capacity (p<0.001). This reduction in LV chamber size is associated with concentric LV hypertrophy and a reciprocal increase in resting heart rate. In addition, cardiac output reserve is further blunted by chronotropic incompetence and a tachycardia-induced LV volume reduction. In conclusion the relationship of exercise capacity and cardiac dimensions described in extreme athletes also applies to patients. Our exploratory analysis suggests that patients who cannot sufficiently exercise have small LV cavities.

[COPD and heart disease]

Cardiovascular diseases are highly prevalent in patients with chronic obstructive pulmonary disease (COPD). Approximately one out of three patients with COPD dies of cardiovascular disease. Overlap syndrome (COPD and obstructive sleep apnea), pulmonary hypertension and lung hyperinflation have a further impact on cardiovascular function in patients with COPD.

Morphologic Response of the Pulmonary Vasculature to Endoscopic Lung Volume Reduction

INTRODUCTION

Endoscopic Lung Volume Reduction has been used to reduce lung hyperinflation in selected patients with severe emphysema. Little is known about the effect of this procedure on the intraparenchymal pulmonary vasculature. In this study we used CT based vascular reconstruction to quantify the effect of the procedure on the pulmonary vasculature.

METHODS

Intraparenchymal vasculature was reconstructed and quantified in 12 patients with CT scans at baseline and 12 weeks following bilateral introduction of sealants in the upper lobes. The volume of each lung and each lobe was measured, and the vascular volume profile was calculated for both lower lobes. The detected vasculature was further labeled manually as arterial or venous in the right lower lobe.

RESULTS

There was an increase in the volume of the lower lobes (3.14L to 3.25L, p=0.0005). There was an increase in BV5, defined as the volume of blood vessels with cross sectional area of less than 5mm², (53.2ml to 57.9ml, p=0.03). This was found to be correlated with the increase in lower lobe volumes (R=0.65, p=0.02). The changes appear to be symmetric for veins and arteries with a correlation coefficient of 0.87 and a slope of near identity.

CONCLUSION

In the subjects studied, there was an increase, from baseline, in BV5 in the lower lobes that correlated with the change in the volume of the lower lobes. The change appeared to be symmetric for both arteries and veins. The study illustrates the use of intraparenchymal pulmonary vascular reconstruction to study morphologic changes in response to interventions.

Endoscopic lung volume reduction with endobronchial valves in patients with severe emphysema and established pulmonary hypertension

BACKGROUND

One of the most common forms of pulmonary hypertension (PH) is that associated with chronic obstructive pulmonary disease (COPD). So far, patients with severe emphysema and established PH have been excluded from endoscopic lung volume reduction (ELVR) therapy due to the risk of right heart decompensation.

OBJECTIVE

The aim of this pilot study was to evaluate the feasibility and efficacy of ELVR using one-way endobronchial valves (EBV) in this specific group of patients.

METHODS

We prospectively included 6 patients with COPD, severe heterogeneous emphysema, and established PH who underwent right heart catheterization and clinical assessments before and 90 days after ELVR with unilateral EBV placement.

RESULTS

This study was not powered to measure any statistical differences in endpoints. Ninety days after ELVR, the symptoms, lung function, and hemodynamics improved in 5 out of 6 patients (1 patient normalized and 1 slightly worsened). The mean hemodynamics improved from baseline to 90 days after ELVR as follows: mean pulmonary artery pressure, -2.5 ± 3.5 mm Hg; pulmonary arterial wedge pressure, -4.3 ± 8.3 mm Hg; cardiac index, +0.3 ± 0.6 l/min/m(2), and 6-min walk distance, +59 ± 99 m. ELVR was performed without PH-related complications in all patients.

CONCLUSION

To our knowledge, this is the first prospective, single-center pilot study to evaluate the feasibility and efficacy of ELVR in patients with established PH. ELVR was feasible and resulted in an improvement of clinical and hemodynamic parameters in 5 out of 6 patients. These results have to be further confirmed in larger-scale controlled studies.

Quantitative computed tomography of pulmonary emphysema and ventricular function in chronic obstructive pulmonary disease patients with pulmonary hypertension

Objective

This study strived to evaluate the relationship between degree of pulmonary emphysema and cardiac ventricular function in chronic obstructive pulmonary disease (COPD) patients with pulmonary hypertension (PH) using electrocardiographic-gated multidetector computed tomography (CT).

Materials and Methods

Lung transplantation candidates with the diagnosis of COPD and PH were chosen for the study population, and a total of 15 patients were included. The extent of emphysema is defined as the percentage of voxels below -910 Hounsfield units in the lung windows in whole lung CT without intravenous contrast. Heart function parameters were measured by electrocardiographic-gated CT angiography. Linear regression analysis was conducted to examine the associations between percent emphysema and heart function indicators.

Results

Significant correlations were found between percent emphysema and right ventricular (RV) measurements, including RV end-diastolic volume (R² = 0.340, p = 0.023), RV stroke volume (R² = 0.406, p = 0.011), and RV cardiac output (R² = 0.382, p = 0.014); the correlations between percent emphysema and left ventricular function indicators were not observed.

Conclusion

The study revealed that percent emphysema is correlated with RV dysfunction among COPD patients with PH. Based on our findings, percent emphysema can be considered for use as an indicator to predict the severity of right ventricular dysfunction among COPD patients.

Cardiopulmonary coupling in chronic obstructive pulmonary disease: the role of imaging

Chronic obstructive pulmonary disorder (COPD) is a systemic disease that affects the cardiovascular system through multiple pathways. Pulmonary hypertension, ventricular dysfunction, and atherosclerosis are associated with smoking and COPD, causing significant morbidity and poor prognosis. Coupling between the pulmonary and cardiovascular system involves mechanical interdependence and inflammatory pathways that potentially affect the entire circulation. Although treatments specific for COPD-related cardiovascular and pulmonary vascular disease are limited, early diagnosis, study of pathophysiology, and monitoring the effects of treatment are enhanced with improved imaging techniques. In this article, we review recent advancements in the imaging of the vasculature and the heart in patients with COPD. We also explore the potential mechanism of coupling between the progression of COPD and vascular disease. Imaging methods reviewed include specific implementations of computed tomography, magnetic resonance imaging, dual-energy computed tomography, positron emission tomography, and echocardiography. Specific applications to the proximal and distal pulmonary vasculature, as well as to the heart and systemic circulation, are also discussed.

Pulmonary hypertension and right heart dysfunction in chronic lung disease

Group 3 pulmonary hypertension (PH) is a common complication of chronic lung disease (CLD), including chronic obstructive pulmonary disease (COPD), interstitial lung disease, and sleep-disordered breathing. Development of PH is associated with poor prognosis and may progress to right heart failure, however, in the majority of the patients with CLD, PH is mild to moderate and only a small number of patients develop severe PH. The pathophysiology of PH in CLD is multifactorial and includes hypoxic pulmonary vasoconstriction, pulmonary vascular remodeling, small vessel destruction, and fibrosis. The effects of PH on the right ventricle (RV) range between early RV remodeling, hypertrophy, dilatation, and eventual failure with associated increased mortality. The golden standard for diagnosis of PH is right heart catheterization, however, evidence of PH can be appreciated on clinical examination, serology, radiological imaging, and Doppler echocardiography. Treatment of PH in CLD focuses on management of the underlying lung disorder and hypoxia. There is, however, limited evidence to suggest that PH-specific vasodilators such as phosphodiesterase-type 5 inhibitors, endothelin receptor antagonists, and prostanoids may have a role in the treatment of patients with CLD and moderate-to-severe PH.

Noninvasive ventilation and lung volume reduction

As parenchymal lung disease in chronic obstructive pulmonary disease becomes increasingly severe there is a diminishing prospect of drug therapies conferring clinically useful benefit. Lung volume reduction surgery is effective in patients with heterogenous upper zone emphysema and reduced exercise tolerance, and is probably underused. Rapid progress is being made in nonsurgical approaches to lung volume reduction, but use outside specialized centers cannot be recommended presently. Noninvasive ventilation given to patients with acute hypercapnic exacerbation of chronic obstructive pulmonary disease reduces mortality and morbidity, but the place of chronic non-invasive ventilatory support remains more controversial.

Impaired left ventricular filling in COPD and emphysema: is it the heart or the lungs? The Multi-Ethnic Study of Atherosclerosis COPD Study

BACKGROUND

COPD and heart failure with preserved ejection fraction overlap clinically, and impaired left ventricular (LV) filling is commonly reported in COPD. The mechanism underlying these observations is uncertain, but may include upstream pulmonary dysfunction causing low LV preload or intrinsic LV dysfunction causing high LV preload. The objective of this study is to determine if COPD and emphysema are associated with reduced pulmonary vein dimensions suggestive of low LV preload.

METHODS

The population-based Multi-Ethnic Study of Atherosclerosis (MESA) COPD Study recruited smokers aged 50 to 79 years who were free of clinical cardiovascular disease. COPD was defined by spirometry. Percent emphysema was defined as regions &lt; -910 Hounsfield units on full-lung CT scan. Ostial pulmonary vein cross-sectional area was measured by contrast-enhanced cardiac magnetic resonance and expressed as the sum of all pulmonary vein areas. Linear regression was used to adjust for age, sex, race/ethnicity, body size, and smoking.

RESULTS

Among 165 participants, the mean (± SD) total pulmonary vein area was 558 ± 159 mm2 in patients with COPD and 623 ± 145 mm2 in control subjects. Total pulmonary vein area was smaller in patients with COPD (-57 mm2; 95% CI, -106 to -7 mm2; P = .03) and inversely associated with percent emphysema (P &lt; .001) in fully adjusted models. Significant decrements in total pulmonary vein area were observed among participants with COPD alone, COPD with emphysema on CT scan, and emphysema without spirometrically defined COPD.

CONCLUSIONS

Pulmonary vein dimensions were reduced in COPD and emphysema. These findings support a mechanism of upstream pulmonary causes of underfilling of the LV in COPD and in patients with emphysema on CT scan.

Factors limiting exercise tolerance in chronic lung diseases

The major limitation to exercise performance in patients with chronic lung diseases is an issue of great importance since identifying the factors that prevent these patients from carrying out activities of daily living provides an important perspective for the choice of the appropriate therapeutic strategy. The factors that limit exercise capacity may be different in patients with different disease entities (i.e., chronic obstructive, restrictive or pulmonary vascular lung disease) or disease severity and ultimately depend on the degree of malfunction or miss coordination between the different physiological systems (i.e., respiratory, cardiovascular and peripheral muscles). This review focuses on patients with chronic obstructive pulmonary disease (COPD), interstitial lung disease (ILD) and pulmonary vascular disease (PVD). ILD and PVD are included because there is sufficient experimental evidence for the factors that limit exercise capacity and because these disorders are representative of restrictive and pulmonary vascular disorders, respectively. A great deal of emphasis is given, however, to causes of exercise intolerance in COPD mainly because of the plethora of research findings that have been published in this area and also because exercise intolerance in COPD has been used as a model for understanding the interactions of different pathophysiologic mechanisms in exercise limitation. As exercise intolerance in COPD is recognized as being multifactorial, the impacts of the following factors on patients' exercise capacity are explored from an integrative physiological perspective: (i) imbalance between the ventilatory capacity and requirement; (ii) imbalance between energy demands and supplies to working respiratory and peripheral muscles; and (iii) peripheral muscle intrinsic dysfunction/weakness.

Chronic obstructive pulmonary disease: clinical integrative physiology

Peripheral airway dysfunction, inhomogeneous ventilation distribution, gas trapping, and impaired pulmonary gas exchange are variably present in all stages of chronic obstructive pulmonary disease (COPD). This article provides a cogent physiologic explanation for the relentless progression of activity-related dyspnea and exercise intolerance that all too commonly characterizes COPD. The spectrum of physiologic derangements that exist in smokers with mild airway obstruction and a history compatible with COPD is examined. Also explored are the perceptual and physiologic consequences of progressive erosion of the resting inspiratory capacity. Finally, emerging information on the role of cardiocirculatory impairment in contributing to exercise intolerance in patients with varying degrees of airway obstruction is reviewed.