Lungs in heart failure

Better Respiratory Function in Heart Failure Patients With Use of Central-Acting Therapeutics

Background

Diaphragm atrophy can contribute to dyspnea in patients with heart failure (HF) with its link to central neurohormonal overactivation. HF medications that cross the blood-brain barrier could act centrally and improve respiratory function, potentially alleviating diaphragmatic atrophy. Therefore, we compared the benefit of central- vs peripheral-acting HF drugs on respiratory function, as assessed by a single cardiopulmonary exercise test (CPET) and outcomes in HF patients.

Methods

A retrospective study was conducted of 624 ambulatory adult HF patients (80% male) with reduced left ventricular ejection fraction ≤ 40% and a complete CPET, followed at a single institution between 2001 and 2017. CPET parameters, and the outcomes all-cause death, a composite endpoint (all-cause death, need for left ventricular assist device, heart transplantation), and all-cause and/or HF hospitalizations, were compared in patients receiving central-acting (n = 550) vs peripheral-acting (n = 74) drugs.

Results

Compared to patients who receive peripheral-acting drugs, patients who receive central-acting drugs had better respiratory function (peak breath-by breath oxygen uptake [VO2], P = 0.020; forced expiratory volume in 1 second [FEV1], P = 0.007), and ventilatory efficiency (minute ventilation / carbon dioxide production [VE/VCO2], P < 0.001; end-tidal carbon dioxide tension [PETCO2], P = 0.015; and trend for forced vital capacity [FVC], P = 0.056). Many of the associations between the CPET parameters and drug type remained significant after multivariate adjustment. Moreover, patients receiving central-acting drugs had fewer composite events (P = 0.023), and HF hospitalizations (P = 0.044), although significance after multivariant correction was not achieved, despite the hazard ratio being 0.664 and 0.757, respectively.

Conclusions

Central-acting drugs were associated with better respiratory function as measured by CPET parameters in HF patients. This could extend to clinically meaningful composite outcomes and hospitalizations but required more power to be definitive in linking to drug effect. Central-acting HF drugs show a role in mitigating diaphragm weakness.

Influence of exertional oscillatory breathing and its temporal behavior in patients with heart failure and reduced ejection fraction

BACKGROUND

Exertional oscillatory breathing (EOV) represents an emerging prognostic marker in heart failure (HF) patients, however little is known about EOV meaning with respect to its disappearance/persistence during cardiopulmonary exercise test (CPET). The present single-center study evaluated EOV clinical and prognostic impact in a large cohort of reduced ejection fraction HF patients (HFrEF) and, contextually, if a specific EOV temporal behavior might be an addictive risk predictor.

METHODS AND RESULTS

Data from 1.866 HFrEF patients on optimized medical therapy were analysed. The primary cardiovascular (CV) study end-point was cardiovascular death, heart transplantation or LV assistance device (LVAD) implantation at 5-years. For completeness a secondary end-point of total mortality at 5- years was also explored. EOV presence was identified in 251 patients (13%): 142 characterized by EOV early cessation (Group A) and 109 by EOV persistence during the whole CPET (Group B). The entire EOV Group showed worse clinical and functional status than NoEOV Group (n = 1.615) and, within the EOV Group, Group B was characterized by a more severe HF. At CV survival analysis, EOV patients showed a poorer outcome than the NoEOV Group (events 27.1% versus 13.1%, p < 0.001) both unpolished and after matching for main confounders. Instead, no significant differences were found between EOV Group A and B with respect to CV outcome. Conversely the analysis for total mortality failed to be significant.

CONCLUSIONS

Our analysis, albeit retrospective, supports the inclusion of EOV into a CPET-centered clinical and prognostic evaluation of the HFrEF patients. EOV characterizes per se a more advanced HFrEF stage with an unfavorable CV outcome. However, the EOV persistence, albeit suggestive of a more severe HF, does not emerge as a further prognostic marker.

Cheyne-stokes respiration in children with heart failure

Cheyne-Stokes respiration (CSA-CSR) is a form of central sleep apnea characterized by alternating periods of hyperventilation and central apneas or hypopneas. CSA-CSR develops following a cardiac insult resulting in a compensatory increase in sympathetic activity, which in susceptible patients causes hyperventilation and destabilizes respiratory control. The physiological changes that occur in CSA-CSR include hyperventilation, a reduced blood gas buffering capacity, and circulatory delay. In adults, 25% to 50% of patients with heart failure are reported to have CSA-CSR. The development of CSA-CSR in this group of patients is considered a poor prognostic sign. The prevalence, progression, and treatment outcomes of CSA-CSR in children remain unclear with only 11 children being described in the literature. The lack of data is possibly not due to the paucity of children with severe heart failure and CSA-CSR but because they may be under-recognized, compounded by the absence of routine polysomnographic assessment of children with moderate to severe heart failure. Building on much broader experience in the diagnosis and management of CSA-CSR in adult sleep medicine and our limited experience in a pediatric quaternary center, this paper will discuss the prevalence of CSA-CSR, its' treatment options, outcomes in children, and the potential future direction for research in this understudied area of pediatric sleep medicine.

Towards Estimation of Tidal Volume and Respiratory Timings via Wearable-Patch-Based Impedance Pneumography in Ambulatory Settings

OBJECTIVE

Evaluating convenient, wearable multi-frequency impedance pneumography (IP)-based respiratory monitoring in ambulatory persons with novel electrode positioning.

METHODS

A wearable multi-frequency IP system was utilized to estimate tidal volume (TV) and respiratory timings in 14 healthy subjects. A 5.1 cm × 5.1 cm tetrapolar electrode array, affixed to the sternum, and a conventional thoracic electrode configuration were employed to measure the respective IP signals, patch and thoracic IP. Data collected during static postures-sitting and supine-and activities-walking and stair-stepping-were evaluated against a simultaneously-obtained spirometer (SP) volume signal.

RESULTS

Across all measurements, estimated TV obtained from the patch and thoracic IP maintained a Pearson correlation coefficient (r) of 0.93 ± 0.05 and 0.95 ± 0.05 to the ground truth TV, respectively, with an associated root-mean-square error (RMSE) of 0.177 L and 0.129 L, respectively. Average respiration rates (RRs) were extracted from 30-second segments with mean-absolute-percentage errors (MAPEs) of 0.93% and 0.74% for patch and thoracic IP, respectively. Likewise, average inspiratory and expiratory timings were identified with MAPEs less than 6% and 4.5% for patch and thoracic IP, respectively.

CONCLUSION

We demonstrated that patch IP performs comparably to traditional, cumbersome IP configurations. We also present for the first time, to the best of our knowledge, that IP can robustly estimate breath-by-breath TV and respiratory timings during ambulation.

SIGNIFICANCE

This work represents a notable step towards pervasive wearable ambulatory respiratory monitoring via the fusion of a compact chest-worn form factor and multi-frequency IP that can be readily adapted for holistic cardiopulmonary monitoring.

Contribution of Peripheral Chemoreceptors to Exercise Intolerance in Heart Failure

Peripheral chemoreceptors (PChRs), because of their strategic localization at the bifurcation of the common carotid artery and along the aortic arch, play an important protective role against hypoxia. Stimulation of PChRs evokes hyperventilation and hypertension to maintain adequate oxygenation of critical organs. A relationship between increased sensitivity of PChRs (hyperreflexia) and exercise intolerance (ExIn) in patients with heart failure (HF) has been previously reported. Moreover, some studies employing an acute blockade of PChRs (e.g., using oxygen or opioids) demonstrated improvement in exercise capacity, suggesting that hypertonicity is also involved in the development of ExIn in HF. Nonetheless, the precise mechanisms linking dysfunctional PChRs to ExIn remain unclear. From the clinical perspective, there are two main factors limiting exercise capacity in HF patients: subjective perception of dyspnoea and muscle fatigue. Both have many determinants that might be influenced by abnormal signalling from PChRs, including: exertional hyperventilation, oscillatory ventilation, ergoreceptor oversensitivity, and augmented sympathetic tone. The latter results in reduced muscle perfusion and altered muscle structure. In this review, we intend to present the milieu of abnormalities tied to malfunctioning PChRs and discuss their role in the complex relationships leading, ultimately, to ExIn.

Prevalence and Prognostic Significance of Pulmonary Function Test Abnormalities in Hospitalized Patients With Acute Decompensated Heart Failure With Preserved and Reduced Ejection Fraction

BACKGROUND

This study evaluated the prevalence and prognostic impact of lung function abnormalities in patients with acute decompensated heart failure (ADHF) with reduced ejection fraction (HFrEF) and preserved ejection fraction (HFpEF).

METHODS AND RESULTS

Of the 1,012 consecutive patients who were admitted to Nara Medical University with ADHF between 2011 and 2018, 657 routinely underwent spirometry (pulmonary function test [PFT]) before discharge. Lung function was classified as normal or abnormal (restrictive, obstructive, or mixed). Abnormal PFTs were seen in 63.0% of patients with ADHF (36.7%, 13.1%, and 13.2% for restrictive, obstructive, and mixed, respectively). The prevalence of abnormal PFT increased with age (P<0.001). Overall, abnormal PFT was an independent predictor of the composite endpoint of cardiovascular mortality or hospitalization for HF (adjusted hazard ratio [HR] 1.402; 95% confidence interval [CI] 1.039-1.914; P=0.027). Abnormal PFT (adjusted HR 2.294; 95% CI 1.368-4.064; P=0.001), as well as the restrictive (HR 2.299; 95% CI 1.322-4.175; P=0.003) and mixed (HR 2.784; 95% CI 1.399-5.581; P=0.004) patterns, were predictive of the composite endpoint in HFpEF, but not in HFrEF.

CONCLUSIONS

Abnormal PFT was prevalent and associated with poor outcomes in ADHF. Spirometry may be a useful tool in patients with ADHF, especially in those with HFpEF, to identify those at higher risk of a poorer outcome.

Noninvasive Ventilation Accelerates Oxygen Uptake Recovery Kinetics in Patients With Combined Heart Failure and Chronic Obstructive Pulmonary Disease

PURPOSE

Oxygen uptake (V˙o2) recovery kinetics appears to have considerable value in the assessment of functional capacity in both heart failure (HF) and chronic obstructive pulmonary disease (COPD). Noninvasive positive pressure ventilation (NIPPV) may benefit cardiopulmonary interactions during exercise. However, assessment during the exercise recovery phase is unclear. The purpose of this investigation was to explore the effects of NIPPV on V˙o2, heart rate, and cardiac output recovery kinetics from high-intensity constant-load exercise (CLE) in patients with coexisting HF and COPD.

METHODS

Nineteen males (10 HF/9 age- and left ventricular ejection fraction-matched HF-COPD) underwent 2 high-intensity CLE tests at 80% of peak work rate to the limit of tolerance (Tlim), receiving either sham ventilation or NIPPV.

RESULTS

Despite greater V˙o2 recovery kinetics on sham, HF-COPD patients presented with a faster exponential time constant τ (76.4 ± 14.0 sec vs 62.8 ± 15.2 sec, P < .05) and mean response time (MRT) (86.1 ± 19.1 sec vs 68.8 ± 12.0 sec, P < .05) with NIPPV and greater ΔNIPPV-sham (τ: 5.6 ± 19.5 vs -25.2 ± 22.4, P < .05; MRT: 4.1 ± 32.2 vs -26.0 ± 19.2, P < .05) compared with HF. There was no difference regarding Tlim between sham and NIPPV in both groups (P < .05).

CONCLUSION

Our results suggest that NIPPV accelerated the V˙o2 recovery kinetics following high-intensity CLE to a greater extent in patients with coexisting HF and COPD compared with HF alone. NIPPV should be considered when the objective is to apply high-intensity interval exercise training as an adjunct intervention during a cardiopulmonary rehabilitation program.

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.

Lung function evaluation in heart failure: possible pitfalls

A 59-year-old male former smoker, with a history of hypertension, diabetes and chronic ischaemic heart disease (prior non-ST-elevation myocardial infarction and percutaneous coronary intervention+stent on circumflex and descending anterior coronary arteries) was referred to our lab for progressive dyspnoea of unknown origin. Even if a temporary moderate left ventricular systolic dysfunction had been observed during the acute phase of non-ST-elevation myocardial infarction, a cardiac ultrasound performed a few months after revascularisation showed a normal systolic function. At the time of the visit, the patient complained of a progressive functional capacity decline in the last 3 months, with shortness of breath after more than usual efforts (New York Heart Association class II). Pharmacological treatment included amlodipine, ivabradine, low dose diuretics, acetylsalicylic acid and metformin. At physical examination rhythmic pulse (70 bpm) and normal arterial pressure (120/70 mmHg) were detected, together with minimal dependent oedema, absence of jugular distention, bibasilar reduced breath sounds with rare fine crackles and soft cardiac tones with grade 2 holosystolic murmur. Resting ECG was normal, except for signs of a previous inferior myocardial infarction. Resting pulmonary function test (PFT) showed a severe restrictive deficit with moderate reduction in lung diffusion for carbon monoxide (D_LCO) entirely due to a reduction in the alveolar volume (V_A). A maximal cardiopulmonary exercise test (CPET) showed a severe reduction in exercise capacity with ventilatory limitation to exercise and a restrictive ventilatory pattern. However, further investigations led to diagnosis of heart failure. Indeed, a chest radiograph (figure 1) showed vascular congestion and pleural effusion, cardiac ultrasound showed a severe reduction in left ventricular systolic function (23.5%) with left ventricular dilation, increased left ventricular filling pressure and pulmonary hypertension and brain natriuretic peptide (BNP) was significantly altered (579 pg·mL⁻¹). A primary lung disease was excluded by computed tomography lung scan.

Close to acute heart failure, a restrictive and/or obstructive lung impairment can be detected in the absence of any primitive lung disease. To avoid diagnostic pitfalls, lung function evaluation should be delayed until after full patient recovery.http://bit.ly/3aEy8ed

Clinical and Physiologic Implications of Negative Cardiopulmonary Interactions in Coexisting Chronic Obstructive Pulmonary Disease-Heart Failure

Chronic obstructive pulmonary disease (COPD) and heart failure with reduced ejection fraction (HF) frequently coexist in the elderly. Expiratory flow limitation and lung hyperinflation due to COPD may adversely affect central hemodynamics in HF. Low lung compliance, increased alveolar-capillary membrane thickness, and abnormalities in pulmonary perfusion because of HF further deteriorates lung function in COPD. We discuss how those negative cardiopulmonary interactions create challenges in clinical interpretation of pulmonary function and cardiopulmonary exercise tests in coexisting COPD-HF. In the light of physiologic concepts, we also discuss the influence of COPD or HF on the current medical treatment of each disease.

Incorporating Lung Diffusing Capacity for Carbon Monoxide in Clinical Decision Making in Chest Medicine

Lung diffusing capacity for carbon monoxide (Dlco) remains the only noninvasive pulmonary function test to provide an integrated picture of gas exchange efficiency in human lungs. Due to its critical dependence on the accessible "alveolar" volume (Va), there remains substantial misunderstanding on the interpretation of Dlco and the diffusion coefficient (Dlco/Va ratio, Kco). This article presents the physiologic and methodologic foundations of Dlco measurement. A clinically friendly approach for Dlco interpretation that takes those caveats into consideration is outlined. The clinical scenarios in which Dlco can effectively assist the chest physician are discussed and illustrative clinical cases are presented.

Effects of bi-level positive airway pressure on ventilatory and perceptual responses to exercise in comorbid heart failure-COPD

This study tested the hypothesis that, by increasing the volume available for tidal expansion (inspiratory capacity, IC), bi-level positive airway pressure (BiPAP™) would lead to greater beneficial effects on dyspnea and exercise intolerance in comorbid heart failure (HF)-chronic obstructive pulmonary disease (COPD) than HF alone. Ten patients with HF and 9 with HF-COPD (ejection fraction = 30 ± 6% and 35 ± 7%; FEV₁ = 83 ± 12% and 65 ± 15% predicted, respectively) performed a discontinuous exercise protocol under sham ventilation or BiPAP™. Time to intolerance increased with BiPAP™ only in HF-COPD (p < 0.05). BiPAP™ led to higher tidal volume and lower duty cycle with longer expiratory time (p < 0.05). Of note, BiPAP™ improved IC (by ∼0.5 l) across exercise intensities only in HF-COPD. These beneficial consequences were associated with lower dyspnea scores at higher levels of ventilation (p < 0.05). By improving the qualitative" (breathing pattern and operational lung volumes) and sensory (dyspnea) features of exertional ventilation, BiPAP™ might allow higher exercise intensities to be sustained for longer during cardiopulmonary rehabilitation in HF-COPD.

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.

The estimation of probability distribution for factor variables with many categorical values

With recent developments of data technology in biomedicine, factor data such as diagnosis codes and genomic features, which can have tens to hundreds of discrete and unorderable categorical values, have emerged. While considered as a fundamental problem in statistical analyses, the estimation of probability distribution for such factor variables has not studied much because the previous studies have mainly focused on continuous variables and discrete factor variables with a few categories such as sex and race. In this work, we propose a nonparametric Bayesian procedure to estimate the probability distribution of factors with many categories. The proposed method was demonstrated through simulation studies under various conditions and showed significant improvements on the estimation errors from the previous conventional methods. In addition, the method was applied to the analysis of diagnosis data of intensive care unit patients, and generated interesting medical hypotheses. The overall results indicate that the proposed method will be useful in the analysis of biomedical factor data.

Sleep Disturbance in Smokers with Preserved Pulmonary Function and with Chronic Obstructive Pulmonary Disease

RATIONALE

Sleep disturbance frequently affects patients with chronic obstructive pulmonary disease (COPD), and is associated with reduced quality of life and poorer outcomes. Data indicate that smokers with preserved pulmonary function have clinical symptoms similar to those meeting spirometric criteria for COPD, but little is known about the driving factors for sleep disturbance in this population of emerging interest.

OBJECTIVES

To compare the magnitude and correlates of sleep disturbance between smokers with preserved pulmonary function and those with airflow obstruction.

METHODS

Using cross-sectional data from the COPD Outcomes-Based Network for Clinical Effectiveness and Research Translation multicenter registry, we identified participants clinically identified as having COPD with a smoking history of at least 20 pack-years and either preserved pulmonary function or airflow obstruction. We quantified sleep disturbance by T-score measured in the sleep disturbance domain of the Patient-Reported Outcomes Information System questionnaire, and defined a minimum important difference as a T-score difference of two points. We performed univariate and multivariable linear regression to evaluate correlates within each group.

RESULTS

We identified 100 smokers with preserved pulmonary function and 476 with airflow obstruction. The sleep disturbance T-score was 4.1 points greater among individuals with preserved pulmonary function (95% confidence interval [CI], 2.0-6.3). In adjusted analyses, depression symptom T-score was associated with sleep disturbance in both groups (airflow obstruction: β, 0.61 points; 95% CI, 0.27-0.94; preserved pulmonary function: β, 0.25 points; 95% CI, 0.12-0.38). Of note, lower percent predicted FEV₁ was associated with greater sleep disturbance among those with preserved pulmonary function (β, -0.19 points; 95% CI, -0.31 to -0.07), whereas higher FEV₁ was associated with greater sleep disturbance among individuals with airflow obstruction (β, 0.06 points; 95% CI, 0.01-0.10).

CONCLUSIONS

Among smokers with clinically identified COPD, the severity of sleep disturbance is greater among those with preserved pulmonary function compared with those with airflow obstruction. Nonrespiratory symptoms, such as depression, were associated with sleep disturbance in both groups, whereas the relationship of sleep disturbance with FEV₁ differed.

Cardiopulmonary Exercise Testing in Patients with Heart Failure with Specific Comorbidities

Exercise capacity is one of the most powerful predicting factors of life expectancy, both in patients with and those without cardiac disease. Cardiopulmonary exercise testing provides a global assessment of the integrative exercise responses involving the pulmonary, cardiovascular, hematopoietic, neuropsychological, and skeletal muscle systems, which are not adequately reflected through the measurement of individual organ system function. This relatively noninvasive, dynamic, physiologic overview allows the evaluation of both submaximal and peak exercise responses, providing the physician with relevant information for clinical decision-making. Chronic heart failure is a significant cause of worldwide mortality and morbidity, whose clinical picture is characterized by exercise intolerance and impaired quality of life. The purpose of this review is to provide an update of the role of cardiopulmonary exercise testing in patients with heart failure with specific comorbidities. Patients with heart failure frequently present concomitant clinical conditions, such as obesity, anemia, lung or kidney disease, diabetes mellitus, cancer, depression, and psychogenic disorders, which could affect length and quality of life, including everyday activities and exercise performance. Poor effort and malingering may be suspected when early discontinuation of the exercise test with irregular breathing occurs.

Impaired left ventricular filling is associated with decreased pulse oximetry values

OBJECTIVES

The aim of this study was to investigate the association between echocardiographic measures of diastolic left ventricular dysfunction and decreased arterial oxyhaemoglobin saturation measured with pulse oximetry (SpO₂).

DESIGN

This is a cross-sectional population-based survey of Norwegian adults. Values obtained using echocardiography, pulse oximetry, and spirometry were included. The primary outcome was abnormal mitral Doppler inflow, defined as normal: E/A ratio 0.75-1.5 and EDT ≥ 140 ms; abnormal: E/A ratio <0.75 or >1.5 or EDT <140 ms. The associations between this outcome and possible predictors, including SpO₂ ≤ 95%, were analysed using univariable and multivariable logistic regression.

RESULTS

A total of 1782 participants aged 50 years or older (54% women, mean age 67.5 years) were included in the analysis. Abnormal mitral Doppler inflow was found in 595 participants. After adjusting for age, gender, previous myocardial infarction, smoking history, dyspnoea, obesity, and decreased lung function, SpO₂ ≤ 95% predicted abnormal mitral Doppler flow with an odds ratio (OR) of 1.6 [95% confidence interval (CI) 1.1-2.4]. Hypertension and BMI > =30 were also significant predictors of impaired filling, with OR of 1.7 (95% CI 1.1-2.7) OR and 1.5 (95% CI 1.2-1.9), respectively.

CONCLUSION

Decreased SpO₂ was a significant predictor of abnormal mitral Doppler flow. Diastolic dysfunction should be considered when SpO₂ ≤ 95% is found.

Central-acting therapeutics alleviate respiratory weakness caused by heart failure-induced ventilatory overdrive

Diaphragmatic weakness is a feature of heart failure (HF) associated with dyspnea and exertional fatigue. Most studies have focused on advanced stages of HF, leaving the cause unresolved. The long-standing theory is that pulmonary edema imposes a mechanical stress, resulting in diaphragmatic remodeling, but stable HF patients rarely exhibit pulmonary edema. We investigated how diaphragmatic weakness develops in two mouse models of pressure overload-induced HF. As in HF patients, both models had increased eupneic respiratory pressures and ventilatory drive. Despite the absence of pulmonary edema, diaphragmatic strength progressively declined during pressure overload; this decline correlated with a reduction in diaphragm cross-sectional area and preceded evidence of muscle weakness. We uncovered a functional codependence between angiotensin II and β-adrenergic (β-ADR) signaling, which increased ventilatory drive. Chronic overdrive was associated with increased PERK (double-stranded RNA-activated protein kinase R-like ER kinase) expression and phosphorylation of EIF2α (eukaryotic translation initiation factor 2α), which inhibits protein synthesis. Inhibition of β-ADR signaling after application of pressure overload normalized diaphragm strength, Perk expression, EIF2α phosphorylation, and diaphragmatic cross-sectional area. Only drugs that were able to penetrate the blood-brain barrier were effective in treating ventilatory overdrive and preventing diaphragmatic atrophy. These data provide insight into why similar drugs have different benefits on mortality and symptomatology, despite comparable cardiovascular effects.

Cardiomyocytes of the Heart and Pulmonary Veins: Novel Contributors to Asthma?

Recent genome-wide association studies have implicated both cardiac and pulmonary vein-related genes in the pathogenesis of asthma. Since cardiac cells are not present in lung airways or viewed to affect the immune system, interpretation of these findings in the context of more well-established contributors to asthma has remained challenging. However, cardiomyocytes are present in the lung, specifically along pulmonary veins, and recent murine models suggest that cardiac cells lining the pulmonary veins may contribute to allergic airway disease. Notably, the cardiac cell-junction protein αT-catenin (αT-cat, CTNNA3), which is implicated in occupational and steroid-resistant asthma by clinical genetic data, appears to play an important role in regulating inflammation around the cardiac cells of pulmonary veins. Beyond the potential contribution of pulmonary veins, clinical data directly examining cardiac function through echocardiography have found strong associations between asthmatic phenotypes and the mechanical properties of the heart. Together, these data suggest that targeting the function of cardiac cells in the pulmonary veins and/or heart may allow for novel and potentially efficacious therapies for asthma, particularly in challenging cases of steroid-resistant asthma.

Influence of heart failure on resting lung volumes in patients with COPD

Objective:

To evaluate the influence of chronic heart failure (CHF) on resting lung volumes in patients with COPD, i.e., inspiratory fraction-inspiratory capacity (IC)/TLC-and relative inspiratory reserve-[1 − (end-inspiratory lung volume/TLC)].

Methods:

This was a prospective study involving 56 patients with COPD-24 (23 males/1 female) with COPD+CHF and 32 (28 males/4 females) with COPD only-who, after careful clinical stabilization, underwent spirometry (with forced and slow maneuvers) and whole-body plethysmography.

Results:

Although FEV₁, as well as the FEV₁/FVC and FEV₁/slow vital capacity ratios, were higher in the COPD+CHF group than in the COPD group, all major "static" volumes-RV, functional residual capacity (FRC), and TLC-were lower in the former group (p < 0.05). There was a greater reduction in FRC than in RV, resulting in the expiratory reserve volume being lower in the COPD+CHF group than in the COPD group. There were relatively proportional reductions in FRC and TLC in the two groups; therefore, IC was also comparable. Consequently, the inspiratory fraction was higher in the COPD+CHF group than in the COPD group (0.42 ± 0.10 vs. 0.36 ± 0.10; p < 0.05). Although the tidal volume/IC ratio was higher in the COPD+CHF group, the relative inspiratory reserve was remarkably similar between the two groups (0.35 ± 0.09 vs. 0.44 ± 0.14; p < 0.05).

Conclusions:

Despite the restrictive effects of CHF, patients with COPD+CHF have relatively higher inspiratory limits (a greater inspiratory fraction). However, those patients use only a part of those limits, probably in order to avoid critical reductions in inspiratory reserve and increases in elastic recoil.

Pulmonary function tests do not predict mortality in patients undergoing continuous-flow left ventricular assist device implantation

OBJECTIVES

To investigate the effect of pulmonary function testing on outcomes after continuous flow left ventricular assist device implantation.

METHODS

A total of 263 and 239 patients, respectively, had tests of forced expiratory volume in 1 second and diffusing capacity of the lungs for carbon monoxide preoperatively for left ventricular assist device implantations between July 2005 and September 2015. Kaplan-Meier analysis and multivariable Cox regressions were performed to evaluate mortality. Patients were analyzed in a single cohort and across 5 groups. Postoperative intensive care unit and hospital lengths of stay were evaluated with negative binomial regressions.

RESULTS

There is no association of forced expiratory volume in 1 second and diffusing capacity of the lungs for carbon monoxide with survival and no difference in mortality at 1 and 3 years between the groups (log rank P = .841 and .713, respectively). Greater values in either parameter were associated with decreased hospital lengths of stay. Only diffusing capacity of the lungs for carbon monoxide was associated with increased intensive care unit length of stay in the group analysis (P = .001). Ventilator times, postoperative pneumonia, reintubation, and tracheostomy rates were similar across the groups.

CONCLUSIONS

Forced expiratory volume in 1 second and diffusing capacity of the lungs for carbon monoxide are not associated with operative or long-term mortality in patients undergoing continuous flow left ventricular assist device implantation. These findings suggest that these abnormal pulmonary function tests alone should not preclude mechanical circulatory support candidacy.

Carvedilol binding to β2-adrenergic receptors inhibits CFTR-dependent anion secretion in airway epithelial cells

Carvedilol functions as a nonselective β-adrenergic receptor (AR)/α1-AR antagonist that is used for treatment of hypertension and heart failure. Carvedilol has been shown to function as an inverse agonist, inhibiting G protein activation while stimulating β-arrestin-dependent signaling and inducing receptor desensitization. In the present study, short-circuit current (Isc) measurements using human airway epithelial cells revealed that, unlike β-AR agonists, which increase Isc, carvedilol decreases basal and 8-(4-chlorophenylthio)adenosine 3',5'-cyclic monophosphate-stimulated current. The decrease in Isc resulted from inhibition of the cystic fibrosis transmembrane conductance regulator (CFTR). The carvedilol effect was abolished by pretreatment with the β2-AR antagonist ICI-118551, but not the β1-AR antagonist atenolol or the α1-AR antagonist prazosin, indicating that its inhibitory effect on Isc was mediated through interactions with apical β2-ARs. However, the carvedilol effect was blocked by pretreatment with the microtubule-disrupting compound nocodazole. Furthermore, immunocytochemistry experiments and measurements of apical CFTR expression by Western blot analysis of biotinylated membranes revealed a decrease in the level of CFTR protein in monolayers treated with carvedilol but no significant change in monolayers treated with epinephrine. These results demonstrate that carvedilol binding to apical β2-ARs inhibited CFTR current and transepithelial anion secretion by a mechanism involving a decrease in channel expression in the apical membrane.

Impact of lung diseases on morbidity and mortality after transcatheter aortic valve implantation: insights from spirometry and body plethysmography

BACKGROUND

The study aims to determine the impact of different lung diseases on morbidity and mortality after transcatheter aortic valve implantation (TAVI).

METHODS

Transcatheter aortic valve implantation was performed transfemoral or transaxillary with CoreValve prosthesis or Edwards SAPIEN prosthesis in patients with symptomatic severe aortic valve stenosis and high surgical risk. Examinations comprised spirometry, body plethysmography echocardiography, and x-ray before TAVI. The primary study end point was death from any cause after TAVI.

RESULTS

During follow-up of 750 ± 538 days, 63 of 212 patients died. Logistic European System for Cardiac Operative Risk Evaluation (hazard risk [HR] 1.032, P < .001), aortic mean gradient (HR 0.96, P < .001), chronic obstructive pulmonary disease (COPD; each degree of COPD: HR 1.436, P = .001), restrictive ventilatory disease (HR 2.252, P = .002), oxygen dependency (HR 3.291, P = .004), and noninvasive ventilation (HR 3.799, P = .005) were independent predictors of long-term mortality. Restrictive ventilatory disease was associated with lower left ventricular ejection fraction, higher B-type natriuretic peptide levels, and pulmonary edema.

CONCLUSION

In patients undergoing TAVI, lung diseases are an independent predictor of all-cause mortality. In particular, oxygen dependency patients and patients with severe COPD and noninvasive ventilation indicate a dismal prognosis. Transcatheter aortic valve implantation seems to have a dubious prognostic benefit in these patients.

The cardiac protein αT-catenin contributes to chemical-induced asthma

Ten to 25% of adult asthma is occupational induced, a subtype caused by exposure to workplace chemicals. A recent genomewide association study identified single-nucleotide polymorphisms in the cardiac protein αT-catenin (αT-cat) that correlated with the incidence and severity of toluene diisocyanate (TDI) occupational asthma. αT-cat is a critical mediator of cell-cell adhesion and is predominantly expressed in cardiomyocytes, but its connection to asthma remains unknown. Therefore, we sought to determine the primary αT-cat-expressing cell type in the lung and its contribution to lung physiology in a murine model of TDI asthma. We show that αT-cat is expressed in lung within the cardiac sheath of pulmonary veins. Mechanically ventilated αT-cat knockout (KO) mice exhibit a significantly increased pressure-volume curve area compared with wild-type (WT) mice, suggesting that αT-cat loss affects lung hysteresis. Using a murine model of TDI asthma, we find that αT-cat KO mice show increased airway hyperresponsiveness to methacholine compared with WT mice. Bronchoalveolar lavage reveals only a mild macrophage-dominant inflammation that is not significantly different between WT and KO mice. These data suggest that αT-cat may contribute to asthma through a mechanism independent of inflammation and related to heart and pulmonary vein dysfunction.