Cor pulmonale: correlation with central airway lesions, peripheral airway lesions, emphysema, and control of breathing

Group 3 Pulmonary Hypertension: From Bench to Bedside

Pulmonary hypertension (PH) because of chronic lung disease is categorized as Group 3 PH in the most recent classification system. Prevalence of these diseases is increasing over time, creating a growing need for effective therapeutic options. Recent approval of the first pulmonary arterial hypertension therapy for the treatment of Group 3 PH related to interstitial lung disease represents an encouraging advancement. This review focuses on molecular mechanisms contributing to pulmonary vasculopathy in chronic hypoxia, the pathology and epidemiology of Group 3 PH, the right ventricular dysfunction observed in this population and clinical trial data that inform the use of pulmonary vasodilators in Group 3 PH.

Chronic Obstructive Pulmonary Disease and the Cardiovascular System: Vascular Repair and Regeneration as a Therapeutic Target

Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality worldwide and encompasses chronic bronchitis and emphysema. It has been shown that vascular wall remodeling and pulmonary hypertension (PH) can occur not only in patients with COPD but also in smokers with normal lung function, suggesting a causal role for vascular alterations in the development of emphysema. Mechanistically, abnormalities in the vasculature, such as inflammation, endothelial dysfunction, imbalances in cellular apoptosis/proliferation, and increased oxidative/nitrosative stress promote development of PH, cor pulmonale, and most probably pulmonary emphysema. Hypoxemia in the pulmonary chamber modulates the activation of key transcription factors and signaling cascades, which propagates inflammation and infiltration of neutrophils, resulting in vascular remodeling. Endothelial progenitor cells have angiogenesis capabilities, resulting in transdifferentiation of the smooth muscle cells via aberrant activation of several cytokines, growth factors, and chemokines. The vascular endothelium influences the balance between vaso-constriction and -dilation in the heart. Targeting key players affecting the vasculature might help in the development of new treatment strategies for both PH and COPD. The present review aims to summarize current knowledge about vascular alterations and production of reactive oxygen species in COPD. The present review emphasizes on the importance of the vasculature for the usually parenchyma-focused view of the pathobiology of COPD.

Cor pulmonale parvus in chronic obstructive pulmonary disease and emphysema: the MESA COPD study

BACKGROUND

The classic cardiovascular complication of chronic obstructive pulmonary disease (COPD) is cor pulmonale or right ventricular (RV) enlargement. Most studies of cor pulmonale were conducted decades ago.

OBJECTIVES

This study sought to examine RV changes in contemporary COPD and emphysema using cardiac magnetic resonance (CMR) imaging.

METHODS

We performed a case-control study nested predominantly in 2 general population studies of 310 participants with COPD and control subjects 50 to 79 years of age with ≥10 pack-years of smoking who were free of clinical cardiovascular disease. RV volumes and mass were assessed using magnetic resonance imaging. COPD and COPD severity were defined according to standard spirometric criteria. The percentage of emphysema was defined as the percentage of lung regions <-950 Hounsfield units on full-lung computed tomography; emphysema subtypes were scored by radiologists. Results were adjusted for age, race/ethnicity, sex, height, weight, smoking status, pack-years, systemic hypertension, and sleep apnea.

RESULTS

Right ventricular end-diastolic volume (RVEDV) was reduced in COPD compared with control subjects (-7.8 ml; 95% confidence interval: -15.0 to -0.5 ml; p = 0.04). Increasing severity of COPD was associated with lower RVEDV (p = 0.004) and lower RV stroke volume (p < 0.001). RV mass and ejection fraction were similar between the groups. A greater percentage of emphysema also was associated with lower RVEDV (p = 0.005) and stroke volume (p < 0.001), as was the presence of centrilobular and paraseptal emphysema.

CONCLUSIONS

RV volumes are lower without significant alterations in RV mass and ejection fraction in contemporary COPD, and this reduction is related to the greater percentage of emphysema on computed tomography.

Mechanisms of cigarette smoke-induced COPD: insights from animal models

Cigarette smoke-induced animal models of chronic obstructive pulmonary disease support the protease-antiprotease hypothesis of emphysema, although which cells and proteases are the crucial actors remains controversial. Inhibition of either serine or metalloproteases produces significant protection against emphysema, but inhibition is invariably accompanied by decreases in the inflammatory response to cigarette smoke, suggesting that these inhibitors do more than just prevent matrix degradation. Direct anti-inflammatory interventions are also effective against the development of emphysema, as are antioxidant strategies; the latter again decrease smoke-induced inflammation. There is increasing evidence for autoimmunity, perhaps directed against matrix components, as a driving force in emphysema. There is intriguing but controversial animal model evidence that failure to repair/failure of lung maintenance also plays a role in the pathogenesis of emphysema. Cigarette smoke produces small airway remodeling in laboratory animals, possibly by direct induction of fibrogenic growth factors in the airway wall, and also produces pulmonary hypertension, at least in part through direct upregulation of vasoactive mediators in the intrapulmonary arteries. Smoke exposure causes goblet cell metaplasia and excess mucus production in the small airways and proximal trachea, but these changes are not good models of either chronic bronchitis or acute exacerbations. Emphysema, small airway remodeling, pulmonary hypertension, and mucus production appear to be at least partially independent processes that may require different therapeutic approaches.

Diffusing capacity in the clinical assessment of chronic airflow limitation

CAL remains an important cause of morbidity and mortality. The diffusing capacity has ranked high in the assessment of CAL because it represents the best pulmonary function test to assess the integrity of the pulmonary capillary bed. Unfortunately, numerous physiologic, pathologic, and technical factors affect the test, thus limiting its sensitivity and specificity. HRCT techniques offer the potential to assess the extent of emphysema more accurately, but the technique requires greater standardization and is more expensive and less noninvasive than DLcoSB testing. Although the CIBA symposium considered DLcoSB "essential" in the investigation of the CAL patient, 16 the use of conventional DLcoSB testing in the seated position at rest is not currently advised as a routine screening procedure. The test must be performed in a center with high degree of quality control, and the results can be of value only by integrating the result into a comprehensive clinical assessment. Within this context, conventional DLcoSB testing may provide limited information about the extent of emphysema because reductions in DLcoSB correlate with the extent of emphysema by HRCT. When DLcoSB is normal, it may point in the direction of considering asthma as the cause of the airflow limitation. It may also provide information about disease severity and prognosis in O2-dependent CAL patients. The test should be a part of the investigation of the patient with unexplained dyspnea. It remains controversial how emphysema correlates with the degree of impairment in CAL, and further work needs to be done to clarify this relationship. This requires a reexamination of current CT methods 110 and the relationship between DLcoSB, structural changes in the lung, and HRCT evidence of emphysema. Refinements in DLcoSB testing methods, such as the measurement of DLcoSB-3EQ are linked to rapidly responding CO analyzers and computer-driven software, which will potentially improve the accuracy and reproducibility of the test, particularly in the presence of airway obstruction and nonuniform distribution of ventilation. Such refinements, which offer the possibility that tests of diffusion could become more useful markers of disease, include measuring DLcoSB when the pulmonary capillary recruitment is near maximal (head-down position, exercise), enhancing the sensitivity of the test to alterations in the lung periphery, standardizing previous volume history, developing more precise corrections for Hb and COHb, and developing an index of diffusion nonuniformity.

Cor pulmonale and silicosis: a necropsy based case-control study

The presence of cor pulmonale at death in relation to other factors such as emphysema, silicosis, and thromboembolism was analysed in a case-control study of 732 South African gold miners. Marked emphysema was the highest risk factor with an odds ratio of 21.32 (95% confidence interval (95% CI) 5.02-90.7), then extensive silicosis (OR 4.95, 95% CI 2.92-8.38) and thromboembolic disease (OR 1.92, 95% CI 1.37-2.69). Age and smoking were not significant predictors of cor pulmonale.