Pulmonary hypertension: evaluation and management

Simulation of Acute Pulmonary Hypertension in Beagle Dogs

Acoustic cardiography (AC) combined with heart sound (HS) recording and electrocardiogram (ECG) provides a noninvasive and inexpensive way to understand the electrical mechanical activity of the heart. Pulmonary artery stenosis can cause hemodynamic abnormalities that might lead to pulmonary hypertension (PH). In this paper, we examined the relationships between the acoustic characteristics of the AC and hemodynamic changes in a beagle dog model of PH.Four healthy beagle dogs were injected with the prostaglandin endoperoxide receptor agonist U-44069 to induce acute PH states. AC was employed to analyze the process of pre-PH, intra-PH, and post-PH. Right ventricular blood pressure (RVBP) was measured via right cardiac catheterization, an invasive method performed in parallel for comparative hemodynamic evaluation. As RVBP increased or decreased, the HS features changed accordingly during acute PH occurrence and development. Right ventricular systolic blood pressure (RVSBP) significantly correlated with the minimum of the first HS (S1) amplitude (correlation coefficient (CC) = -0.82), energy of the S1 (CC = 0.86), energy of the second HS (S2) (CC = 0.67), entropy of the S1 (CC = -0.94), and ratio of electromechanical systolic time (EMST) to the cardiac cycle time (CC = 0.81). The two techniques (AC [HSs and ECG] versus right cardiac catheterization [RVBP]) were significantly correlated. Especially, the diastolic filling time (DFT) had a significant relationship with the right ventricular diastolic time (RVDT) (CC = 0.97), perfusion time (PT) (CC = 0.96), and cardiac cycle time (RR) (CC = 0.96). The CCs between the RVDT and the max dp/dt to min dp/dt, the EMST and the Q to min dp/dt, and the electromechanical activation time and the Q to max dp/dt were 0.95, 0.99, and 0.86, respectively. Furthermore, the logistic regression model with different combinations was used to identify the effective features for monitoring hemodynamic and pathophysiologic conditions.AC provided significant insight into mechanical dysfunction in a rapid and noninvasive way that could be used for early screening of PH.

Clinical Value of FeNO for Pulmonary Hypertension Diagnosis in Patients with Acute Exacerbation of Chronic Obstructive Pulmonary Disease

Objective

To investigate the clinical value of fractional exhaled nitric oxide (FeNO) in the diagnosis of pulmonary hypertension (PH) in patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD).

Methods

In this study, the medical records of AECOPD patients were retrospectively reviewed. The patients were divided into AECOPD and AECOPD + PH groups based on the absence or presence of PH. Moreover, FeNO and other indexes were compared between the two groups. The value of FeNO in diagnosing AECOPD with PH was determined using the ROC curve.

Results

A total of 83 patients were enrolled (56 in the AECOPD group and 27 in the AECOPD + PH group). The level of FeNO was significantly lower in the AECOPD + PH group than in the AECOPD group (P = 0.022). Moreover, FeNO level (25.22 ± 8.45 ppb) was higher in the mild PH subgroup than in the moderate (16.64 ± 5.67 ppb, P = 0.005) or severe (11.75 ± 2.36, P = 0.002) PH subgroups. FeNO level was positively correlated with C-reactive protein in AECOPD patients while negatively correlated with brain natriuretic peptide in the AECOPD + PH group. ROC analysis showed that the optimal cutoff value of FeNO in the diagnosis of AECOPD with PH was 24.5 ppb.

Conclusion

FeNO level at admission can act as an indicator for PH diagnosis in AECOPD patients.

Presence and outcomes of kidney disease in patients with pulmonary hypertension

BACKGROUND AND OBJECTIVES

Pulmonary hypertension is associated with higher mortality rates. The associations of nondialysis-dependent CKD and all-cause mortality in patients with pulmonary hypertension were studied.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

The study population included those patients who underwent right heart catheterization for confirmation of pulmonary hypertension between 1996 and January 2011. Pulmonary hypertension was defined as the presence of mean pulmonary artery pressure ≥ 25 mmHg at rest measured by right heart catheterization. CKD was defined as the presence of two measurements of eGFR<60 ml/min per 1.73 m(2) 90 days apart. The risk factors associated with CKD as well as the association between CKD and death in those patients with pulmonary hypertension using logistic regression and Cox proportional hazard models were examined.

RESULTS

Of 1088 patients with pulmonary hypertension, 388 (36%) patients had CKD: 340 patients had stage 3 CKD, and 48 (4%) patients had stage 4 CKD. In the multivariable analysis, older age, higher hemoglobin, and higher mean right atrial pressures were independently associated with CKD. During a median follow-up of 3.2 years (interquartile range=1.5-5.6 years), 559 patients died. After adjusting for relevant covariates, presence of stage 3 CKD (hazard ratio, 1.37; 95% confidence interval, 1.14 to 1.66) and stage 4 CKD (hazard ratio, 2.69; 95% confidence interval, 1.88 to 3.86) was associated with all-cause mortality in those patients with pulmonary hypertension. When eGFR was examined as a continuous measure, a 5 ml/min per 1.73 m(2) lower eGFR was associated with a 5% (95% confidence interval, 1.03 to 1.07) higher hazard for death. This higher risk with CKD was similar irrespective of demographics, left ventricular function, and pulmonary capillary wedge pressure.

CONCLUSION

In a clinical population referred for right heart catheterization, presence of CKD was associated with higher all-cause mortality in those patients with pulmonary hypertension. Mechanisms that may underlie these associations warrant additional studies.

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.

Update on exhaled nitric oxide in pulmonary disease

The ability to assess the inflammatory status of a patient's airway using a noninvasive method is the ideal situation for clinicians. Owing in part to the relationship between the levels of exhaled nitric oxide to inflammation and the ease of the technique, the measurement of the fraction of exhaled nitric oxide (F(E)NO) has achieved considerable attention, particularly with respect to asthma. A multitude of studies have shown that when measured in exhaled air, this unique molecule has the potential to have both diagnostic and therapeutic roles in the clinical setting for many pulmonary diseases. The incorporation of F(E)NO into asthma management and treatment algorithms may help shed further insight on the current control and future risk of patients. Research is ongoing to determine the biology and the benefits of the use of F(E)NO in respiratory conditions in addition to asthma. This review will briefly outline the pathophysiology of nitric oxide, the measurement of F(E)NO and the potential clinical uses of F(E)NO in asthma and a number of other respiratory diseases. Despite its promise, until further research is conducted, the use of F(E)NO cannot be recommended for routine clinical management of respiratory diseases at present, but should be considered as an adjuvant to help guide therapy in certain patients with asthma and in those with eosinophilic bronchitis.

Ambrisentan

Ambrisentan, an orally active, highly selective antagonist of the endothelin-1 type A receptor, is indicated for the treatment of pulmonary arterial hypertension (PAH). It has a low potential for drug-drug interactions and requires only once-daily administration. Three months' treatment with ambrisentan 2.5-10 mg/day significantly improved exercise capacity, as determined by the distance walked in 6 minutes (6MWD; primary outcome measure), compared with placebo in two double-blind, multicenter studies in patients with PAH (ARIES-1 [n = 202] and -2 [n = 192]). A decrease in dyspnea and a delay in clinical worsening were among the improvements in secondary outcomes generally observed with ambrisentan versus placebo. In ARIES-E, a 2-year extension of ARIES-1 and -2, approved dosages of ambrisentan (5 and 10 mg/day) were associated with a sustained improvement in 6MWD, a generally sustained improvement in dyspnea, and a low risk of clinical worsening and of death. Six months' treatment with ambrisentan 5 mg/day significantly improved 6MWD (primary outcome measure) and dyspnea relative to baseline in an open-label, non-comparative, multicenter study in a diverse population of patients with PAH or non-PAH forms of pulmonary hypertension (ARIES-3 [n = 224]). Ambrisentan was associated with a low risk of clinical worsening and of death. Ambrisentan treatment was generally well tolerated in the various ARIES trials. All available pre-registration and post-marketing data indicate the drug poses only a very low risk of liver injury; the 'black box' warning regarding potential liver injury has been removed from the US prescribing information for ambrisentan.

Exhaled nitric oxide in pulmonary diseases: a comprehensive review

The upregulation of nitric oxide (NO) by inflammatory cytokines and mediators in central and peripheral airway sites can be monitored easily in exhaled air. It is now possible to estimate the predominant site of increased fraction of exhaled NO (FeNO) and its potential pathologic and physiologic role in various pulmonary diseases. In asthma, increased FeNO reflects eosinophilic-mediated inflammatory pathways moderately well in central and/or peripheral airway sites and implies increased inhaled and systemic corticosteroid responsiveness. Recently, five randomized controlled algorithm asthma trials reported only equivocal benefits of adding measurements of FeNO to usual clinical guideline management including spirometry; however, significant design issues may exist. Overall, FeNO measurement at a single expiratory flow rate of 50 mL/s may be an important adjunct for diagnosis and management in selected cases of asthma. This may supplement standard clinical asthma care guidelines, including spirometry, providing a noninvasive window into predominantly large-airway-presumed eosinophilic inflammation. In COPD, large/central airway maximal NO flux and peripheral/small airway/alveolar NO concentration may be normal and the role of FeNO monitoring is less clear and therefore less established than in asthma. Furthermore, concurrent smoking reduces FeNO. Monitoring FeNO in pulmonary hypertension and cystic fibrosis has opened up a window to the role NO may play in their pathogenesis and possible clinical benefits in the management of these diseases.

Membrane rafts and caveolae in cardiovascular signaling

PURPOSE OF REVIEW

Substantial evidence documents the key role of lipid (membrane) rafts and caveolae as microdomains that concentrate a wide variety of receptors and postreceptor components regulated by hormones, neurotransmitters and growth factors.

RECENT FINDINGS

Recent data document that these microdomains are important in regulating vascular endothelial and smooth muscle cells and renal epithelial cells, and particularly in signal transduction across the plasma membrane.

SUMMARY

Raft/caveolae domains are cellular regions, including in cardiovascular and renal epithelial cells, which organize a large number of signal transduction components, thereby providing spatially and temporally efficient regulation of cell function.