Dysregulation of endogenous carbon monoxide and nitric oxide production in patients with advanced ischemic or nonischemic cardiomyopathy

Exhaled nitric oxide as a biomarker in COPD and related comorbidities

Chronic Obstructive Pulmonary Disease (COPD) is defined as a disease characterized by persistent, progressive airflow limitation. Recent studies have underlined that COPD is correlated to many systemic manifestations, probably due to an underlying pattern of systemic inflammation. In COPD fractional exhaled Nitric Oxide (FeNO) levels are related to smoking habits and disease severity, showing a positive relationship with respiratory functional parameters. Moreover FeNO is increased in patients with COPD exacerbation, compared with stable ones. In alpha-1 antitrypsin deficiency, a possible cause of COPD, FeNO levels may be monitored to early detect a disease progression. FeNO measurements may be useful in clinical setting to identify the level of airway inflammation, per se and in relation to comorbidities, such as pulmonary arterial hypertension and cardiovascular diseases, either in basal conditions or during treatment. Finally, some systemic inflammatory diseases, such as psoriasis, have been associated with higher FeNO levels and potentially with an increased risk of developing COPD. In these systemic inflammatory diseases, FeNO monitoring may be a useful biomarker for early diagnosis of COPD development.

Right ventricular afterload and the role of nitric oxide metabolism in left-sided heart failure

Awareness has grown in recent years that right ventricular (RV) function is equally important as left ventricular (LV) function in the setting of left-sided heart disease. RV dysfunction can be the consequence of an increased afterload imposed by the failing LV. The concept of "afterload" is physically most correctly described by vascular input impedance. However, for clinical purposes, afterload is most often modeled to consist of 3 components; pulmonary vascular resistance (PVR), pulmonary arterial compliance (PAC), and characteristic impedance. Whereas PVR is historically most described, PAC (which represents the distensibility of the vasculature) has rapidly gained recognition for its prognostic ability in both pulmonary arterial hypertension and left-sided heart disease. Owing to the specific anatomy of the pulmonary circulation, PVR and PAC have an inverse hyperbolic relationship, which position can be shifted by varying wedge pressures. Knowledge of the afterload components helps one to understand how elevated left-sided filling pressures increase pulsatile load on the RV. An increase in resistive load (known as "reactive" or "out-of-proportion" pulmonary hypertension) ultimately complements the increase in pulsatile load. Perturbations in nitric oxide metabolism are thought to be crucial in this evolution and have therefore been sought as a major therapeutic target.

Increased exhaled nitric oxide levels after exercise in patients with chronic systolic heart failure with pulmonary venous hypertension

BACKGROUND

Fractional exhaled nitric oxide (eNO) is recognized as a marker of pulmonary endothelial function. Oxidative stress is associated with systemic endothelial nitric oxide production, but its correlation with eNO in heart failure (HF) patients has not been described. Previous studies have reported increased eNO levels after exercise in symptomatic HF patients but decreased levels with pulmonary arterial hypertension. Our objective was to prospectively examine the potential myocardial and functional determinants of exercise-induced rise of eNO in HF.

METHODS AND RESULTS

Thirty-four consecutive ambulatory patients with chronic systolic HF (left ventricular ejection fraction [LVEF] ≤45%) underwent symptom-limited cardiopulmonary stress testing and echocardiography. eNO was determined immediately after exercise. Systemic endothelial dysfunction was assessed by asymmetric dimethylarginine (ADMA) and the L-arginine/ADMA ratio. In our study cohort (mean age 53 ± 13 years, 76% male, median LVEF 31%, interquartile range [IQR] 25%-40%), the mean eNO was 23 ± 9 ppb. eNO levels were higher in patients with diastolic dysfunction stages 2 or 3 than stage 1 or normal diastology (26.1 ± 9 vs 19.5 ± 7 ppb; P = .013). eNO had a positive correlation with estimated systolic pulmonary artery pressure (r = 0.57; P = .0009) and indexed left atrium volume (r = 0.43; P = .014), but it did not correlate with cardiopulmonary exercise test parameters, ADMA, or symptom score.

CONCLUSIONS

In contrast to earlier reports, the increase in postexercise eNO observed in stable chronic systolic HF patients may be attributed to the presence of underlying pulmonary venous hypertension probably secondary to advanced diastolic dysfunction.

Cardiovascular biomarkers in exhaled breath

With each breath that we exhale, thousands of molecules are expelled in our breath, giving individuals a "breath-print" that can tell a lot about them and their state of health. Breath analysis is rapidly evolving as the new frontier in medical testing. The end of the 20th century and the beginning of the 21st century have arguably witnessed a revolution in our understanding of the constituents of exhaled breath and the development of the field of breath analysis and testing. Thanks to major breakthroughs in new technologies (infrared, electrochemical, chemiluminescence, and others) and the availability of mass spectrometers, the field of breath analysis has made considerable advances in the 21st century. Several methods are now in clinical use or nearly ready to enter that arena. Breath analysis has the potential to offer relatively inexpensive, rapid, noninvasive methods for detecting and/or monitoring a variety of diseases. Breath analysis also has applications in fields beyond medicine, including environmental monitoring, security, and others. This review will focus on exhaled breath as a potential source of biomarkers for medical applications with specific attention to applications (and potential applications) in cardiovascular disease.

Cardiovascular biomarkers in exhaled breath

With each breath that we exhale, thousands of molecules are expelled in our breath, giving individuals a "breath-print" that can tell a lot about them and their state of health. Breath analysis is rapidly evolving as the new frontier in medical testing. The end of the 20th century and the beginning of the 21st century have arguably witnessed a revolution in our understanding of the constituents of exhaled breath and the development of the field of breath analysis and testing. Thanks to major breakthroughs in new technologies (infrared, electrochemical, chemiluminescence, and others) and the availability of mass spectrometers, the field of breath analysis has made considerable advances in the 21st century. Several methods are now in clinical use or nearly ready to enter that arena. Breath analysis has the potential to offer relatively inexpensive, rapid, noninvasive methods for detecting and/or monitoring a variety of diseases. Breath analysis also has applications in fields beyond medicine, including environmental monitoring, security, and others. This review will focus on exhaled breath as a potential source of biomarkers for medical applications with specific attention to applications (and potential applications) in cardiovascular disease.

Carbon monoxide: endogenous production, physiological functions, and pharmacological applications

Over the last decade, studies have unraveled many aspects of endogenous production and physiological functions of carbon monoxide (CO). The majority of endogenous CO is produced in a reaction catalyzed by the enzyme heme oxygenase (HO). Inducible HO (HO-1) and constitutive HO (HO-2) are mostly recognized for their roles in the oxidation of heme and production of CO and biliverdin, whereas the biological function of the third HO isoform, HO-3, is still unclear. The tissue type-specific distribution of these HO isoforms is largely linked to the specific biological actions of CO on different systems. CO functions as a signaling molecule in the neuronal system, involving the regulation of neurotransmitters and neuropeptide release, learning and memory, and odor response adaptation and many other neuronal activities. The vasorelaxant property and cardiac protection effect of CO have been documented. A plethora of studies have also shown the importance of the roles of CO in the immune, respiratory, reproductive, gastrointestinal, kidney, and liver systems. Our understanding of the cellular and molecular mechanisms that regulate the production and mediate the physiological actions of CO has greatly advanced. Many diseases, including neurodegenerations, hypertension, heart failure, and inflammation, have been linked to the abnormality in CO metabolism and function. Enhancement of endogenous CO production and direct delivery of exogenous CO have found their applications in many health research fields and clinical settings. Future studies will further clarify the gasotransmitter role of CO, provide insight into the pathogenic mechanisms of many CO abnormality-related diseases, and pave the way for innovative preventive and therapeutic strategies based on the physiologic effects of CO.