Vasoreactivity to inhaled nitric oxide with oxygen predicts long-term survival in pulmonary arterial hypertension

Calcium channel blockers in patients with pulmonary arterial hypertension receiving PAH-specific treatment

BACKGROUND

Calcium channel blockers (CCB) are the first effective therapy for vasoreactive patients with idiopathic pulmonary arterial hypertension (IPAH). However, the advent of modern PAH-specific drugs may undermine the role of vasoreactivity tests and CCB treatment. We aimed to clarify the effect of acute vasoreactivity testing and CCB on patients with IPAH receiving PAH-specific treatment.

METHODS

We retrospectively investigated consecutive patients with IPAH (n = 136) diagnosed between 2000 and 2020 and collected data from patients who underwent acute vasoreactivity testing using inhaled nitric oxide (NO). The effects of vasoreactivity testing and CCB therapy were reviewed. Long-term survival was analysed using the Kaplan-Meier method.

RESULTS

Acute vasoreactivity testing was performed in 49% of patients with IPAH (n = 67), including 23 patients (34%) receiving PAH-specific therapy without vasoreactivity testing. Eight patients (12%), including three patients (4.4%) receiving PAH-specific therapy, presented acute responses at vasoreactivity testing. They received high-dose CCB therapy (CCB monotherapy for five patients [7.5%] and CCB therapy and PAH-specific therapy for three patients [4.4%]). They presented a significant improvement in clinical parameters and near-normalisation of haemodynamics (mean pulmonary arterial pressure decreased from 46 [interquartile range: 40-49] to 19.5 [interquartile range: 18-23] mmHg [P < .001] at 1-year follow-up). All eight vasoreactive responders receiving CCB therapy showed better long-term survival than non-responders treated with PAH-specific therapy (P < .001).

CONCLUSIONS

CCB therapy benefited patients with IPAH who showed acute response to vasoreactivity testing using inhaled NO, even when receiving modern PAH-specific therapy. Acute vasoreactive responders may benefit more from CCB than from PAH-specific therapy.

Circulating Biomarkers in Pulmonary Arterial Hypertension: An Update

Pulmonary arterial hypertension (PAH) is a rare subtype of group 1 pulmonary hypertension (PH) diseases, characterized by high pulmonary artery pressure leading to right ventricular dysfunction and potential life-threatening consequences. PAH involves complex mechanisms: vasoconstriction, vascular remodeling, endothelial dysfunction, inflammation, oxidative stress, fibrosis, RV remodeling, cellular hypoxia, metabolic imbalance, and thrombosis. These mechanisms are mediated by several pathways, involving molecules like nitric oxide and prostacyclin. PAH diagnosis requires clinical evaluation and right heart catheterization, confirming a value of mPAP ≥ 20 mmHg at rest and often elevated pulmonary vascular resistance (PVR). Even if an early and accurate diagnosis is crucial, PAH still lacks effective biomarkers to assist in its diagnosis and prognosis. Biomarkers could contribute to arousing clinical suspicion and serve for prognosis prediction, risk stratification, and dynamic monitoring in patients with PAH. The aim of the present review is to report the main novelties on new possible biomarkers for the diagnosis, prognosis, and treatment monitoring of PAH.

Can Inhaled Nitric Oxide Response Predict Tolerance to Therapies and Survival in Patients With Combined Precapillary and Postcapillary Pulmonary Hypertension?

Inhaled nitric oxide (iNO) relaxes the pulmonary circulation and variably increases the left ventricular preload and pulmonary artery wedge pressure (PAWP)-hemodynamic information that may help guide treatment decisions and assess prognosis in patients with combined precapillary and postcapillary pulmonary hypertension (PH). We included consecutive patients with combined precapillary and postcapillary PH (mean pulmonary artery pressure >20 mm Hg, PAWP >15 mm Hg, and pulmonary vascular resistance [PVR] >2 Woods unit [WU]) who underwent right-sided cardiac catheterization with iNO at the Cleveland Clinic Pulmonary Vascular Disease program between 2017 and 2022. We included 104 patients with baseline PAWP and PVR of 22.2 ± 4.2 mm Hg and 6.1 ± 3.2 WU, respectively. Pulmonary arterial hypertension (PAH) with postcapillary component and PH left heart disease with precapillary component were identified in 27 (26%) and 77 patients (74%), respectively. No side effects were noted during the administration of iNO. During iNO, the PVR decreased 1.1 ± 1.4 WU and the PAWP increased 1.3 ± 3.7 mm Hg. A more pronounced increase in PAWP with iNO was associated with a decrease in PVR (R -0.35, p <0.001) and increase in stroke volume (R 0.20, p = 0.046). Tolerance to PAH-specific medications, overall survival, and heart failure hospitalizations were not significantly associated with the change in PAWP or PVR with iNO. In conclusion, in patients with combined precapillary and postcapillary PH, iNO challenge is safe and caused a significant decrease in PVR, with an increase in PAWP. The changes in PAWP and PVR during iNO administration were not associated with tolerance to PAH-specific medications, heart failure-related hospitalization, or survival.

Inhaled nitric oxide: can it serve as a savior for COVID-19 and related respiratory and cardiovascular diseases?

Nitric oxide (NO), as an important gaseous medium, plays a pivotal role in the human body, such as maintaining vascular homeostasis, regulating immune-inflammatory responses, inhibiting platelet aggregation, and inhibiting leukocyte adhesion. In recent years, the rapid prevalence of coronavirus disease 2019 (COVID-19) has greatly affected the daily lives and physical and mental health of people all over the world, and the therapeutic efficacy and resuscitation strategies for critically ill patients need to be further improved and perfected. Inhaled nitric oxide (iNO) is a selective pulmonary vasodilator, and some studies have demonstrated its potential therapeutic use for COVID-19, severe respiratory distress syndrome, pulmonary infections, and pulmonary hypertension. In this article, we describe the biochemistry and basic characteristics of NO and discuss whether iNO can act as a "savior" for COVID-19 and related respiratory and cardiovascular disorders to exert a potent clinical protective effect.

Frequency of acute vasodilator response (AVR) in incident and prevalent patients with pulmonary arterial hypertension: Results from the pulmonary vascular disease phenomics study

The prevalence of acute vasodilator response (AVR) to inhaled nitric oxide (iNO) during right heart catheterization (RHC) is 12% in idiopathic pulmonary arterial hypertension (IPAH). AVR, however, is reportedly lower in other disease-associated pulmonary arterial hypertension (PAH), such as connective tissue disease (CTD). The prevalence of AVR in patients on PAH therapy (prevalent cases) is unknown. We sought to determine AVR prevalence in Group 1 PH in the PVDOMICS cohort of incident and prevalent patients undergoing RHC. AVR was measured in response to 100% O2 and O2 plus iNO, with positivity defined as (1) decrease in mean pulmonary artery pressure (mPAP) by ≥10 mmHg to a value ≤40 mmHg, with no change or an increase in cardiac output (definition 1); or (2) decrease in mPAP by ≥12% and pulmonary vascular resistance by ≥30% (definition 2). AVR rates and cumulative survival were compared between incident and prevalent patients. In 338 mainly prevalent (86%) patients, positive AVR to O2-only was <2%, and 5.1% to 16.9%, based on definition 1 and 2 criteria, respectively; following O2 + iNO. IPAH AVR prevalence (4.1%-18.7%) was similar to prior reports. AVR positivity was 7.7% to 15.4% in mostly CTD-PAH prevalent cases, and 2.6% to 11.8% in other PAH groups. Survival was 89% in AVR responders versus 77% in nonresponders from PAH diagnosis, and 91% versus 86% from PVDOMICS enrollment (log-rank test p = 0.04 and p = 0.05, respectively). In conclusion, AVR in IPAH patients is similar to prior studies. AVR in non-IPAH patients was higher than previously reported. The relationship between PAH therapy, AVR response, and survival warrants further investigation.

Prognostic value of follow-up vasoreactivity test in pulmonary arterial hypertension

BACKGROUND

Acute vasoreactivity test with inhaled nitric oxide (NO) is performed during diagnostic right heart catheterization (RHC) to identify patients with pulmonary arterial hypertension (PAH) who respond to calcium channel blockers. Our purpose was to investigate the prognostic importance of follow-up vasoreactivity test after treatment.

METHODS

We retrospectively analyzed 36 PAH patients (mean age, 47 years; 61 % treatment-naïve), who underwent diagnostic and follow-up RHC and vasoreactivity tests at our center. The primary outcome was all-cause mortality.

RESULTS

The median time between baseline and follow-up RHC was 9.7 months. Absolute change in mean pulmonary arterial pressure (ΔmPAP) during NO challenge was less pronounced after treatment, but there was great variability among patients. Overall cohort was dichotomized into two groups: preserved vasoreactivity (ΔmPAP ≤ -1 mmHg) and less vasoreactivity (ΔmPAP ≥0 mmHg) at follow-up RHC. Less vasoreactivity group had higher usage rate of endothelin receptor antagonists and parenteral prostacyclin analogues. During a median observation period of 6.3 years after follow-up RHC, 7 patients died, of which 6 showed less vasoreactivity at follow-up. Absolute ΔmPAP ≥0 at follow-up RHC was associated with all-cause mortality in univariable Cox regression analysis (hazard ratio, 8.728; 95 % confidence interval, 1.045-72.887; p = 0.045), whereas other hemodynamic parameters were not. Absolute ΔmPAP ≥0 at follow-up RHC was associated with all-cause mortality in multivariable Cox analysis adjusted for age and known PAH prognostic factors (HR, 12.814; 95 % CI, 1.088-150.891; p = 0.043). Kaplan-Meier survival analysis revealed a significantly worse survival of less vasoreactivity group compared to preserved vasoreactivity group (log-rank test, p = 0.016).

CONCLUSIONS

Follow-up vasoreactivity test after treatment could contribute to the detection of high-risk subgroups who might need careful monitoring and referral for lung transplantation.

Acute vasoreactivity testing during right heart catheterization in chronic thromboembolic pulmonary hypertension: Results from the pulmonary vascular disease phenomics study

Chronic thromboembolic pulmonary hypertension (CTEPH) is believed to involve both vascular obstruction and vasoconstriction; hence, pulmonary vasodilators such as riociguat may be beneficial. Acute vasoreactivity testing (AVT) is seldom performed routinely in CTEPH patients, so there is limited understanding of the frequency and significance of an acute vasodilator response. Systematic vasodilator testing with oxygen (O₂) and oxygen plus inhaled nitric oxide (O₂ + iNO) was performed as part of the Pulmonary Vascular Disease Omics (PVDOMICS) NHLBI project, providing an opportunity to examine AVT responses in CTEPH. Patients with CTEPH enrolled in PVDOMICS (n = 49, 40 with prevalent CTEPH [82%]) underwent right heart catheterization including AVT with O₂ and O₂ + iNO. Hemodynamics were obtained at baseline and with each challenge. Fourteen of 49 patients (29%) had >20% drop in pulmonary vascular resistance (PVR) with O₂. With O₂ + iNO, 30/49 (61%) had >20% drop in PVR, 20% had >20% drop in mean pulmonary artery pressure (mPAP) and PVR, and 8% had >10 mmHg decline in mPAP to mPAP < 40 with normal cardiac output. Patients on riociguat had less response to O₂ + iNO than patients on phosphodiesterase-5 inhibitors. Our findings shed light on the significant variability in vascular tone that is present in CTEPH, confirming that CTEPH represents a combination of mechanical obstruction and vasoconstriction that appears similar to that observed with Group 1 PAH. Additional study regarding whether results of acute vasodilator testing predict response to therapy and relate to prognosis is warranted.

Long-term prognostic value of cardiac catheterization and acute vasodilator testing with inhaled iloprost in pediatric idiopathic pulmonary arterial hypertension

To assess the long-term prognostic value of cardiac catheterization and acute vasodilator testing (AVT) with inhaled iloprost in children with idiopathic pulmonary arterial hypertension (IPAH). Data on 81 consecutive children with IPAH referred to our center who underwent cardiac catheterization and AVT between June 2008 and August 2019 were collected. The correlation between the invasive hemodynamic data and transplant-free survival was analyzed. Twenty-four patients died and 1 underwent lung transplantation during a median follow-up of 3.8 years, with a 5-year transplant-free survival rate of 64.9%. Univariate analysis showed that predictors associated with improved survival included a lower pulmonary vascular resistance index (PVRI), PVRI/systemic vascular resistance index (SVRI), mean pulmonary arterial pressure (mPAP)/mean systemic arterial pressure, mean right atrial pressure, and a higher cardiac index (CI), mixed systemic venous oxygen saturations (SvO₂), and acute vasodilator response (AVR) according to the Barst criteria (decrease in mPAP and PVRI/SVRI ratio of >20% without a decrease in CI). In multivariate Cox regression analysis, Barst AVR and SvO₂ were independently related to transplant-free survival. Multiple hemodynamic variables from cardiac catheterization and AVT with inhaled iloprost have important prognostic value for long-term survival in children with IPAH, of which pulmonary vasoreactivity defined by the Barst criteria and SvO₂ are independent prognostic factors.

Nitric oxide: Clinical applications in critically ill patients

Inhaled nitric oxide (iNO) acts as a selective pulmonary vasodilator and it is currently approved by the FDA for the treatment of persistent pulmonary hypertension of the newborn. iNO has been demonstrated to effectively decrease pulmonary artery pressure and improve oxygenation, while decreasing extracorporeal life support use in hypoxic newborns affected by persistent pulmonary hypertension. Also, iNO seems a safe treatment with limited side effects. Despite the promising beneficial effects of NO in the preclinical literature, there is still a lack of high quality evidence for the use of iNO in clinical settings. A variety of clinical applications have been suggested in and out of the critical care environment, aiming to use iNO in respiratory failure and pulmonary hypertension of adults or as a preventative measure of hemolysis-induced vasoconstriction, ischemia/reperfusion injury and as a potential treatment of renal failure associated with cardiopulmonary bypass. In this narrative review we aim to present a comprehensive summary of the potential use of iNO in several clinical conditions with its suggested benefits, including its recent application in the scenario of the COVID-19 pandemic. Randomized controlled trials, meta-analyses, guidelines, observational studies and case-series were reported and the main findings summarized. Furthermore, we will describe the toxicity profile of NO and discuss an innovative proposed strategy to produce iNO. Overall, iNO exhibits a wide range of potential clinical benefits, that certainly warrants further efforts with randomized clinical trials to determine specific therapeutic roles of iNO.

Perfusion imaging heterogeneity during NO inhalation distinguishes pulmonary arterial hypertension (PAH) from healthy subjects and has potential as an imaging biomarker

BACKGROUND

Without aggressive treatment, pulmonary arterial hypertension (PAH) has a 5-year mortality of approximately 40%. A patient's response to vasodilators at diagnosis impacts the therapeutic options and prognosis. We hypothesized that analyzing perfusion images acquired before and during vasodilation could identify characteristic differences between PAH and control subjects.

METHODS

We studied 5 controls and 4 subjects with PAH using HRCT and ¹³NN PET imaging of pulmonary perfusion and ventilation. The total spatial heterogeneity of perfusion (CV²_Qtotal) and its components in the vertical (CV²_Qvgrad) and cranio-caudal (CV²_Qzgrad) directions, and the residual heterogeneity (CV²_Qr), were assessed at baseline and while breathing oxygen and nitric oxide (O₂ + iNO). The length scale spectrum of CV²_Qr was determined from 10 to 110 mm, and the response of regional perfusion to O₂ + iNO was calculated as the mean of absolute differences. Vertical gradients in perfusion (Q_vgrad) were derived from perfusion images, and ventilation-perfusion distributions from images of ¹³NN washout kinetics.

RESULTS

O₂ + iNO significantly enhanced perfusion distribution differences between PAH and controls, allowing differentiation of PAH subjects from controls. During O₂ + iNO, CV²_Qvgrad was significantly higher in controls than in PAH (0.08 (0.055-0.10) vs. 6.7 × 10^-3 (2 × 10^-4-0.02), p < 0.001) with a considerable gap between groups. Q_vgrad and CV²_Qtotal showed smaller differences: - 7.3 vs. - 2.5, p = 0.002, and 0.12 vs. 0.06, p = 0.01. CV²_Qvgrad had the largest effect size among the primary parameters during O₂ + iNO. CV²_Qr, and its length scale spectrum were similar in PAH and controls. Ventilation-perfusion distributions showed a trend towards a difference between PAH and controls at baseline, but it was not statistically significant.

CONCLUSIONS

Perfusion imaging during O2 + iNO showed a significant difference in the heterogeneity associated with the vertical gradient in perfusion, distinguishing in this small cohort study PAH subjects from controls.

Management of Pulmonary Hypertension in the Pediatric Patient

Pediatric pulmonary hypertension (PH) is a rare disease with historically very high morbidity and mortality. In the past 20 years, there has been a growing recognition that pediatric PH, although having similarities to adult PH, is a unique entity with its own particular pathogeneses, presentation, and management. With better understanding and earlier diagnosis of pediatric PH, and as more medications have become available, survival of children with PH has also significantly improved. This article reviews the various forms of PH in childhood, with a focus on both established and investigational therapies that are available for children with PH.

Thromboinflammatory Biomarkers in COVID-19: Systematic Review and Meta-analysis of 17,052 Patients

Objective

To evaluate differences in thromboinflammatory biomarkers between patients with severe coronavirus disease 2019 (COVID-19) infection/death and mild infection.

Patients and Methods

MEDLINE, Cochrane Central Register of Controlled Trials, EMBASE, EBSCO, Web of Science, and CINAHL databases were searched for studies comparing thromboinflammatory biomarkers in COVID-19 among patients with severe COVID-19 disease or death (severe/nonsurvivors) and those with nonsevere disease or survivors (nonsevere/survivors) from January 1, 2020, through July 11, 2020. Inclusion criteria were (1) hospitalized patients 18 years or older comparing severe/nonsurvivors vs nonsevere/survivors and (2) biomarkers of inflammation and/or thrombosis. A random-effects model was used to estimate the weighted mean difference (WMD) between the 2 groups of COVID-19 severity.

Results

We included 75 studies with 17,052 patients. The severe/nonsurvivor group was older, had a greater proportion of men, and had a higher prevalence of hypertension, diabetes, cardiac or cerebrovascular disease, chronic kidney disease, malignancy, and chronic obstructive pulmonary disease. Thromboinflammatory biomarkers were significantly higher in patients with severe disease, including D-dimer (WMD, 0.60; 95% CI, 0.49 to 0.71; I²=83.85%), fibrinogen (WMD, 0.42; 95% CI, 0.18 to 0.67; I²=61.88%; P<.001), C-reactive protein (CRP) (WMD, 35.74; 95% CI, 30.16 to 41.31; I²=85.27%), high-sensitivity CRP (WMD, 62.68; 95% CI, 45.27 to 80.09; I²=0%), interleukin 6 (WMD, 22.81; 95% CI, 17.90 to 27.72; I²=90.42%), and ferritin (WMD, 506.15; 95% CI, 356.24 to 656.06; I²=52.02%). Moderate to significant heterogeneity was observed for all parameters (I² > 25%). Subanalysis based on disease severity, mortality, and geographic region of the studies revealed similar inferences.

Conclusion

Thromboinflammatory biomarkers (D-dimer, fibrinogen, CRP, high-sensitivity CRP, ferritin, and interleukin 6) and marker of end-organ damage (high-sensitivity troponin I) are associated with increased severity and mortality in COVID-19 infection.

Noninvasive detection of impaired pulmonary artery endothelial function in people living with HIV

OBJECTIVE

People living with HIV (PLWH) have an increased risk of pulmonary vascular disease and pulmonary hypertension. Endothelial cell dysfunction is thought to contribute, but human studies have been limited by the invasive nature of conventional measures of pulmonary artery endothelial function (PAEF). We report here a noninvasive MRI approach to measure nitric oxide mediated PAEF by quantifying changes in pulmonary artery area and blood flow during isometric handgrip exercise (IHE), an endothelial nitric oxide dependent stressor. We used this to test the hypothesis that PLWH have impaired PAEF, even before development of pulmonary hypertension.

DESIGN

A prospective cohort study.

METHODS

We enrolled 25 HIV-positive viral-suppressed individuals on stable antiretroviral therapy without known or suspected pulmonary hypertension and 19 matched seronegative control individuals (HIV-negative). Pulmonary artery area and blood flow changes in response to IHE were measured with noncontrast MRI. Data previously collected during nitric oxide-synthase inhibition were analysed to determine the role of nitric oxide in the pulmonary artery response to IHE.

RESULTS

Seronegative individuals exhibited the anticipated PA vasodilatory response to IHE, but this was completely absent in HIV-positive individuals who exhibited an impaired area change (-1.1 ± 1.2 vs. +7.7 ± 2.2%, HIV-positive vs. HIV-negative, mean ± SEM, respectively, P = 0.002) and blood flow response (0.2 ± 2.3 vs. 13.5 ± 4.8%, P = 0.005). The pulmonary artery vasodilatory effect of IHE in healthy individuals was fully blocked by nitric oxide-synthase, demonstrating this pulmonary artery response is predominantly nitric oxide mediated.

CONCLUSION

Using noninvasive MRI methods to quantify PAEF, we observed significantly impaired PAEF in PLWH compared with matched HIV-negative controls. Noninvasive PAEF testing may be useful in evaluating early HIV-related pulmonary vascular disease.

Treatment-related biomarkers in pulmonary hypertension patients on oral therapies

Background

Multiple classes of oral therapy are available for the treatment of pulmonary arterial hypertension (PAH), but there is little to guide clinicians in choosing a specific regimen or therapeutic class. We aimed to investigate whether treatment-relevant blood biomarkers can predict therapy response in prevalent PAH patients.

Methods

This prospective cohort study longitudinally assessed biomarkers along the endothelin-1 (ET-1) and nitric oxide (cGMP, ADMA, SDMA, nitrite, and S-nitrosohemoglobin) pathways along with the cGMP/NT-proBNP ratio over 12 months in patients with WHO Group 1 PAH on oral PAH-specific therapies. The relationship between biomarkers and 6MWD at the same and future visits was examined using mixed linear regression models adjusted for age. As cGMP can be elevated when NT-proBNP is elevated, we also tested the relationship between 6MWD and the cGMP/NT-pro BNP ratio. Patients with PAH with concomitant heart or lung disease or chronic thromboembolic pulmonary hypertension (CTEPH) were included in a sensitivity analysis.

Results

The study cohort included 58 patients with PAH treated with either an endothelin receptor antagonist (27.6%), phosphodiesterase-5 inhibitor (25.9%) or a combination of the two (43.1%). Among biomarkers along the current therapeutic pathways, ET-1 and the cGMP/NT-proBNP ratio associated with same visit 6MWD (p = 0.02 and p = 0.03 respectively), and ET-1 predicted future 6MWD (p = 0.02). ET-1 (p = 0.01) and cGMP/NT-proBNP ratio (p = 0.04) also predicted future 6MWD in the larger cohort (n = 108) of PAH patients with concomitant left heart disease (n = 17), lung disease (n = 20), or CTEPH (n = 13). Finally, in the larger cohort, SDMA associated with 6MWD at the same visit (p = 0.01) in all subgroups and ADMA associated with 6MWD in PAH patients with concomitant lung disease (p = 0.03) and PAH patients on ERA therapy (p = 0.01).

Conclusions

ET-1, cGMP/NTproBNP ratio, and dimethylarginines ADMA and SDMA are mediators along pathways targeted by oral PAH therapies that associate with or predict 6MWD.

Predictors of mortality in hospitalized COVID-19 patients: A systematic review and meta-analysis

Mortality rates of coronavirus disease-2019 (COVID-19) continue to rise across the world. Information regarding the predictors of mortality in patients with COVID-19 remains scarce. Herein, we performed a systematic review of published articles, from 1 January to 24 April 2020, to evaluate the risk factors associated with mortality in COVID-19. Two investigators independently searched the articles and collected the data, in accordance with PRISMA guidelines. We looked for associations between mortality and patient characteristics, comorbidities, and laboratory abnormalities. A total of 14 studies documenting the outcomes of 4659 patients were included. The presence of comorbidities such as hypertension (odds ratio [OR], 2.5; 95% confidence interval [CI], 2.1-3.1; P < .00001), coronary heart disease (OR, 3.8; 95% CI, 2.1-6.9; P < .00001), and diabetes (OR, 2.0; 95% CI, 1.7-2.3; P < .00001) were associated with significantly higher risk of death amongst patients with COVID-19. Those who died, compared with those who survived, differed on multiple biomarkers on admission including elevated levels of cardiac troponin (+44.2 ng/L, 95% CI, 19.0-69.4; P = .0006); C-reactive protein (+66.3 µg/mL, 95% CI, 46.7-85.9; P < .00001); interleukin-6 (+4.6 ng/mL, 95% CI, 3.6-5.6; P < .00001); D-dimer (+4.6 µg/mL, 95% CI, 2.8-6.4; P < .00001); creatinine (+15.3 µmol/L, 95% CI, 6.2-24.3; P = .001); and alanine transaminase (+5.7 U/L, 95% CI, 2.6-8.8; P = .0003); as well as decreased levels of albumin (-3.7 g/L, 95% CI, -5.3 to -2.1; P < .00001). Individuals with underlying cardiometabolic disease and that present with evidence for acute inflammation and end-organ damage are at higher risk of mortality due to COVID-19 infection and should be managed with greater intensity.

Current Status and Future Opportunities in Lung Precision Medicine Research with a Focus on Biomarkers. An American Thoracic Society/National Heart, Lung, and Blood Institute Research Statement

BACKGROUND

Thousands of biomarker tests are either available or under development for lung diseases. In many cases, adoption of these tests into clinical practice is outpacing the generation and evaluation of sufficient data to determine clinical utility and ability to improve health outcomes. There is a need for a systematically organized report that provides guidance on how to understand and evaluate use of biomarker tests for lung diseases.

METHODS

We assembled a diverse group of clinicians and researchers from the American Thoracic Society and leaders from the National Heart, Lung, and Blood Institute with expertise in various aspects of precision medicine to review the current status of biomarker tests in lung diseases. Experts summarized existing biomarker tests that are available for lung cancer, pulmonary arterial hypertension, idiopathic pulmonary fibrosis, asthma, chronic obstructive pulmonary disease, sepsis, acute respiratory distress syndrome, cystic fibrosis, and other rare lung diseases. The group identified knowledge gaps that future research studies can address to efficiently translate biomarker tests into clinical practice, assess their cost-effectiveness, and ensure they apply to diverse, real-life populations.

RESULTS

We found that the status of biomarker tests in lung diseases is highly variable depending on the disease. Nevertheless, biomarker tests in lung diseases show great promise in improving clinical care. To efficiently translate biomarkers into tests used widely in clinical practice, researchers need to address specific clinical unmet needs, secure support for biomarker discovery efforts, conduct analytical and clinical validation studies, ensure tests have clinical utility, and facilitate appropriate adoption into routine clinical practice.

CONCLUSIONS

Although progress has been made toward implementation of precision medicine for lung diseases in clinical practice in certain settings, additional studies focused on addressing specific unmet clinical needs are required to evaluate the clinical utility of biomarkers; ensure their generalizability to diverse, real-life populations; and determine their cost-effectiveness.

Pulmonary Arterial Hypertension

This article provides an overview of pulmonary arterial hypertension (PAH), beginning with the initial pathologic recognition of pulmonary hypertension more than 100 years ago and progressing to the current diagnostic categorization of PAH. It reviews the epidemiology, pathophysiology, genetics, and modern treatment of PAH. The article discusses several important recent studies that have highlighted the importance of new management strategies, including serial risk assessment and combination pharmacotherapy.

Methamphetamine and the risk of pulmonary arterial hypertension

PURPOSE OF REVIEW

Methamphetamine is a highly addictive drug originally developed for the treatment of neuropsychiatric disorders. At present, the epidemic rise of illicit methamphetamine use has increased the number of patients living with medical complications. Our group has recently identified a definite association between methamphetamine use and pulmonary arterial hypertension (PAH), a life-threatening disease characterized by occlusive vasculopathy and progressive right heart failure. This review will discuss the evidence that links methamphetamine with PAH and how to approach the diagnosis and management of methamphetamine-associated pulmonary arterial hypertension (Meth-APAH) patients in clinic.

RECENT FINDINGS

Compared with idiopathic (I) PAH, Meth-APAH patients present with worse functional status, right ventricular dysfunction, and exercise tolerance. Despite therapy, the 5-year survival of Meth-APAH patients is significantly lower compared with IPAH. Genetic studies suggest that loss of function variants in genes involved in drug detoxification can increase susceptibility for methamphetamine-related vascular injury and trigger occlusive vasculopathy.

SUMMARY

PAH patients undergoing diagnostic evaluation should be screened for a history of current or past methamphetamine use. Pharmacovigilance should be implemented to monitor patients being treated with methamphetamine for neuropsychiatric disorders (e.g., attention-deficit hyperactivity disorder). More studies will be needed to identify which susceptibility factors increase risk of PAH in methamphetamine users.

Diagnosing and managing scleroderma-related pulmonary arterial hypertension

Scleroderma is an uncommon autoimmune disease of unknown cause that may affect any organ system in the body. Patients with scleroderma are prone to developing pulmonary complications, including pulmonary arterial hypertension (PAH), that are the leading cause of death in this population. This article describes scleroderma-related PAH and its diagnosis and management.

Development of a portable mini-generator to safely produce nitric oxide for the treatment of infants with pulmonary hypertension

OBJECTIVES

To test the safety of a novel miniaturized device that produces nitric oxide (NO) from air by pulsed electrical discharge, and to demonstrate that the generated NO can be used to vasodilate the pulmonary vasculature in rabbits with chemically-induced pulmonary hypertension.

STUDY DESIGN

A miniature NO (mini-NO) generator was tested for its ability to produce therapeutic levels (20-80 parts per million (ppm)) of NO, while removing potentially toxic gases and metal particles. We studied healthy 6-month-old New Zealand rabbits weighing 3.4 ± 0.4 kg (mean ± SD, n = 8). Pulmonary hypertension was induced by chemically increasing right ventricular systolic pressure to 28-30 mmHg. The mini-NO generator was placed near the endotracheal tube. Production of NO was triggered by a pediatric airway flowmeter during the first 0.5 s of inspiration.

RESULTS

In rabbits with acute pulmonary hypertension, the mini-NO generator produced sufficient NO to induce pulmonary vasodilation. Potentially toxic nitrogen dioxide (NO₂) and ozone (O₃) were removed by the Ca(OH)₂ scavenger. Metallic particles, released from the electrodes by the electric plasma, were removed by a 0.22 μm filter. While producing 40 ppm NO, the mini-NO generator was cooled by a flow of air (70 ml/min) and the external temperature of the housing did not exceed 31 °C.

CONCLUSIONS

The mini-NO generator safely produced therapeutic levels of NO from air. The mini-NO generator is an effective and economical approach to producing NO for treating neonatal pulmonary hypertension and will increase the accessibility and therapeutic uses of life-saving NO therapy worldwide.

Pulmonary Delivery of Therapeutic and Diagnostic Gases

The 21st Congress for the International Society for Aerosols in Medicine included, for the first time, a session on Pulmonary Delivery of Therapeutic and Diagnostic Gases. The rationale for such a session within ISAM is that the pulmonary delivery of gaseous drugs in many cases targets the same therapeutic areas as aerosol drug delivery, and is in many scientific and technical aspects similar to aerosol drug delivery. This article serves as a report on the recent ISAM congress session providing a synopsis of each of the presentations. The topics covered are the conception, testing, and development of the use of nitric oxide to treat pulmonary hypertension; the use of realistic adult nasal replicas to evaluate the performance of pulsed oxygen delivery devices; an overview of several diagnostic gas modalities; and the use of inhaled oxygen as a proton magnetic resonance imaging (MRI) contrast agent for imaging temporal changes in the distribution of specific ventilation during recovery from bronchoconstriction. Themes common to these diverse applications of inhaled gases in medicine are discussed, along with future perspectives on development of therapeutic and diagnostic gases.

Nitric oxide and pulmonary arterial hypertension

The pathogenesis of pulmonary arterial hypertension remains undefined. Changes in the expression and effects mediated by a number of vasoactive factors have been implicated to play a role in the onset and progression of the disease. The source of many of these mediators, such as nitric oxide (NO), prostacyclin and endothelin-1 (ET-1), is the pulmonary endothelium. This article focus in the role of nitric oxide in PAH, reviewing the evidence for its involvement in regulation of pulmonary a vascular tone under physiological conditions, the mechanisms by which it can contribute to the pathological changes seen in PAH and strategies for the use of NO as a therapy for treatment of the disease.

Combined oral administration of L-arginine and tetrahydrobiopterin in a rat model of pulmonary arterial hypertension

Alterations in the nitric oxide (NO) pathway play a major role in pulmonary arterial hypertension (PAH). L-arginine (LA) and tetrahydrobiopterin (BH₄) are main substrates in the production of NO, which mediates pulmonary vasodilation. Administration of either LA or BH₄ decrease pulmonary artery pressure (PAP). A combined administration of both may have synergistic effects in the therapy of PAH. In a telemetrically monitored model of unilateral pneumonectomy and monocrotaline-induced PAH, male Sprague-Dawley rats received either LA (300 mg/kg; n = 15), BH₄ (20 mg/kg; n = 15), the combination of LA and BH₄ (300 mg/kg, 20 mg/kg; n = 15), or vehicle (control group; n = 10) from day 28 after monocrotaline induction. Therapy was orally administered once daily over consecutive 14 days. LA, BH₄, or both equally lowered PAP, increased pulmonary vascular elasticity, restored spontaneous locomotoric activity, prevented body weight loss and palliated small vessel disease of severely pulmonary hypertensive rats. BH₄ substitution lowered asymmetric dimethylarginine levels sustainably at 60 min after administration and downregulated endothelial NO synthase mRNA expression. No significant survival, macro- and histomorphologic or hemodynamic differences were found between therapy groups at the end of the study period. Administration of LA and BH₄ both mediated a decrease of mean PAP, attenuated right ventricular hypertrophy and small vessel disease in monocrotaline-induced pulmonary hypertensive rats, though a combined administration of both substances did not reveal any synergistic therapy effects in our animal model.

Identifying "super responders" in pulmonary arterial hypertension

Pharmacotherapeutic options for pulmonary arterial hypertension (PAH) have increased dramatically in the last two decades and along with this have been substantial improvements in survival. Despite these advances, however, PAH remains a progressive and ultimately fatal disease for most patients and only epoprostenol has been shown to improve survival in a randomized control trial. Clinical observations of the heterogeneity of treatment response to different classes of medications across the phenotypically diverse PAH population has led to the identification of patients who derive significantly more benefit from certain medications than the population mean, the so-called "super responders." This was first recognized among PAH patients with acute vasodilator response during invasive hemodynamic testing, a subset of whom have dramatically improved survival when treated with calcium channel blocker (CCB) therapy. Retrospective studies have now suggested a sex discrepancy in response to endothelin receptor antagonists (ERA) and phosphodiesterase inhibitors, and more recently a few studies have found genomic associations with response to CCBs and ERAs. With increasing availability of "omics" technologies, recognition of these "super responders," combined with careful clinical and molecular phenotyping, will lead to advances in pharmacogenomics, precision medicine, and continued improvements in survival among PAH patients.

Preoperative Assessment of the Impact of Positive Pressure Ventilation With Noninvasive Positive Pressure Ventilation in a Patient With Eisenmenger Syndrome: A Case Study

In Eisenmenger syndrome (ES), positive pressure ventilation (PPV) during general anesthesia may lead to an increase in pulmonary vascular resistance and potentially to hypoxemia. In an attempt to predict the patient's hemodynamic response to intraoperative ventilation, we tested preoperatively the hemodynamic effects of noninvasive PPV with continuous positive pressure in a woman with ES scheduled for oophorectomy. The surgery was performed without complications, and the patient was discharged on postoperative day 8.

Physiological Techniques and Pulmonary Hypertension - Left Heart Disease

Group 2 Pulmonary hypertension (PH) is associated with left heart disease (LHD;Group 2 PH) and is the most common form of PH. Group 2 PH represents an important subgroup of patients with LHD where the development of PH leads to a significant increase in morbidity and mortality. Early diagnosis may provide an opportunity to intervene and significantly delay progression. In addition to clinical suspicion, several approaches including hemodynamic assessment, exercise testing, and imaging techniques play an important role in better disease characterization and management. Here, we review the role of physiologic based hemodynamic and exercise assessments of Group 2 PH patients.

Role of Vasodilator Testing in Pulmonary Hypertension

Pulmonary hypertension is clinically defined by a mean pulmonary artery (PA) pressure of 25mm Hg or more at rest, as measured by right heart catheterization. To identify patients who are likely to have a beneficial response to calcium channel blockers (CCBs) and therefore a better prognosis, acute vasodilator testing should be performed in patients in certain subsets of pulmonary arterial hypertension (PAH). A near normalization of pulmonary hemodynamics is needed before patients can be considered for therapy with CCBs. Intravenous adenosine, intravenous epoprostenol, inhaled nitric oxide, or inhaled iloprost are the standard agents used for vasoreactivity testing in patients with idiopathic PAH. In this review we describe the various aspects of vasodilator testing including the rationale, pathophysiology and agents used in the procedure.

The heterogeneity of clinical practice patterns among an international cohort of pulmonary arterial hypertension experts

The extent to which pulmonary arterial hypertension (PAH) experts share common practice patterns that are in alignment with published expert consensus recommendations is unknown. Our objective was to characterize the clinical management strategies used by an international cohort of self-identified PAH experts. A 32-item questionnaire composed mainly of rank order or Likert scale questions was distributed via the Internet (August 5, 2013, through January 20, 2014) to four international pulmonary vascular disease organizations. The survey respondents (N = 105) were field experts reporting 11.6 ± 8.7 years of PAH experience. Likert scale responses (1 = disagree, 7 = agree) were 3.0-5.0, indicating a disparity in opinions, for 78% of questions. Respondent (dis)agreement scores were 4.4 ± 2.2 for use of expert recommendations to determine catheterization timing in PAH. For PAH patients without cardiogenic shock or known vasoreactivity status, the most and least preferred first-line therapies (1 = most preferred, 5 = least preferred) were phosphodiesterase type 5 inhibitors (PDE-Vi) and subcutaneous prostacyclin analogues, respectively (1.4 ± 0.8 vs. 4.0 ± 1.1; P < 0.05). Compared with US-practicing clinicians (N = 46), non-US-practicing clinicians (N = 57) favored collaboration between cardiology and pulmonary medicine for clinical decision making (1 = disagree, 7 = agree; 3.1 ± 2.2 vs. 4.8 ± 2.2; P < 0.0001) and PDE-Vi (6.5% vs. 22.4%) as first-line therapy for PAH patients with cardiogenic shock but were less likely to perform vasoreactivity testing in patients with lung disease-induced pulmonary hypertension (4.3 ± 2.1 vs. 2.2 ± 1.6; P < 0.0001). In conclusion, practice patterns among PAH experts diverge from consensus recommendations and differ by practice location, suggesting that opportunity may exist to improve care quality for this highly morbid cardiopulmonary disease.

Prognostic value of acute vasodilator response in pulmonary arterial hypertension: beyond the "classic" responders

BACKGROUND

A "classic" response to acute vasodilator testing (drop of >10 mm Hg in mean pulmonary artery pressure [mPAP] to <40 mm Hg) confers an excellent prognosis in patients with idiopathic pulmonary arterial hypertension (IPAH) and identifies candidates for treatment with calcium channel blockers (CCB). Little is known about vasodilator responsiveness (VR) in other types of PAH, or about outcomes in patients with a significant but "non-classic" decrease in mPAP. We hypothesized that VR occurs in non-idiopathic PAH and non-classic VR portends a better prognosis than no VR in PAH.

METHODS

Acute VR testing with nitric oxide was performed on 155 consecutive patients referred for PH evaluation. Non-classic response was defined as decrease in mPAP >10 mm Hg to >40 mm Hg with preserved cardiac output. Demographics and functional status were assessed at baseline and the first clinic visit after VR testing, and survival was followed over time.

RESULTS

Twenty patients (13%) displayed classic VR. Among classic responders, 12 (60%) had IPAH and 8 (40%) had connective tissue disease-associated PAH (CTD-PAH); however, only responders with IPAH had improved survival compared with non-responders (p = 0.02). Thirteen patients (8%) had a non-classic VR. Non-classic response was not associated with improved survival compared with non-responders (p = 0.86). Acute change in mPAP or pulmonary vascular resistance in the entire cohort did not predict survival.

CONCLUSIONS

Classic acute VR occurs in CTD-PAH as well as IPAH; however, only IPAH patients have improved outcomes. A significant but non-classic VR is not associated with improved survival.

Hemodynamics should be the primary approach to diagnosing, following, and managing pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a highly morbid cardiopulmonary disease characterized by plexogenic pulmonary arteriole remodelling. Importantly, PAH severity correlates inversely with cardiac output and directly with pulmonary vascular resistance and right atrial pressure, illustrating the importance of accurately measured hemodynamics to define the clinical profile of patients. Currently available noninvasive technology offers only hemodynamic estimates. In contrast, right heart catheterization is the principle diagnostic procedure in PAH and is required to: (1) definitively exclude alternative pulmonary vascular diseases; and (2) quantify hemodynamics at baseline, after vasoreactivity testing, or in response to therapy to prognosticate outcome and guide therapeutic escalation.

Current clinical management of pulmonary arterial hypertension

During the past 2 decades, there has been a tremendous evolution in the evaluation and care of patients with pulmonary arterial hypertension (PAH). The introduction of targeted PAH therapy consisting of prostacyclin and its analogs, endothelin antagonists, phosphodiesterase-5 inhibitors, and now a soluble guanylate cyclase activator have increased therapeutic options and potentially reduced morbidity and mortality; yet, none of the current therapies have been curative. Current clinical management of PAH has become more complex given the focus on early diagnosis, an increased number of available therapeutics within each mechanistic class, and the emergence of clinically challenging scenarios such as perioperative care. Efforts to standardize the clinical care of patients with PAH have led to the formation of multidisciplinary PAH tertiary care programs that strive to offer medical care based on peer-reviewed evidence-based, and expert consensus guidelines. Furthermore, these tertiary PAH centers often support clinical and basic science research programs to gain novel insights into the pathogenesis of PAH with the goal to improve the clinical management of this devastating disease. In this article, we discuss the clinical approach and management of PAH from the perspective of a single US-based academic institution. We provide an overview of currently available clinical guidelines and offer some insight into how we approach current controversies in clinical management of certain patient subsets. We conclude with an overview of our program structure and a perspective on research and the role of a tertiary PAH center in contributing new knowledge to the field.

Comparison of acute hemodynamic effects of inhaled nitric oxide and inhaled epoprostenol in patients with pulmonary hypertension

Inhaled nitric oxide (iNO) is used for acute vasoreactivity testing in pulmonary arterial hypertension (PAH) patients. Inhaled epoprostenol (iPGI₂) has pulmonary selectivity and is less costly. We sought to compare acute hemodynamic effects of iNO (20 ppm) and iPGI₂ (50 ng/kg/min) and determine whether their combination has additive effects. We conducted a prospective, single center, randomized, cross-over study in 12 patients with PAH and seven with heart failure with preserved ejection fraction (HFpEF). In PAH patients, iNO lowered mean pulmonary artery pressure (mPAP) by 9 ± 12% and pulmonary vascular resistance (PVR) by 14 ± 32% (mean ± SD). iPGI₂ decreased mPAP by 10 ± 12% and PVR by 12 ± 36%. Responses to iNO and iPGI₂ in mPAP and PVR were directly correlated (r² = 0.68, 0.70, respectively, P < 0.001). In HFpEF patients, mPAP dropped by 4 ± 7% with each agent, and PVR dropped by 33 ± 23% with iNO, and by 25 ± 29% with iPGI₂ (P = NS). Pulmonary artery wedge pressure (PAWP) increased significantly with iPGI₂ versus baseline (20 ± 3 vs. 17 ± 2 mmHg, P = 0.02) and trended toward an increase with iNO and the combination (20 ± 2, 19 ± 4 mmHg, respectively). There were no additive effects in either group. In PAH patients, the vasodilator effects of iNO and iPGI₂ correlated at the doses used, making iPGI₂ a possible alternative for testing acute vasoreactivity, but their combination lacks additive effect. Exposure of HFpEF patients to inhaled vasodilators worsens the PAWP without hemodynamic benefit.

Protocol for vasoreactivity testing with epoprostenol in pulmonary hypertension

Vascular remodeling of distal pulmonary arterioles that promotes abnormal pulmonary vascular reactivity is a central mechanism in the pathogenesis of pulmonary arterial hypertension (PAH). In selected patients, invasive pulmonary vasoreactivity testing performed in the cardiac catheterization laboratory with inhaled nitric oxide, epoprostenol, or adenosine is useful for PAH diagnosis, risk stratification, and assessing patient appropriateness for PAH-specific treatment(s). Limited accessibility to inhaled nitric oxide and a suboptimal test sensitivity profile reported for adenosine has contributed to the selection of epoprostenol for pulmonary vasoreactivity testing in some pulmonary hypertension referral centers. However, standardized procedural protocols for administrating epoprostenol for this purpose are largely unavailable to the practicing clinical community. The current work aims to bridge this gap by providing a stepwise procedure for the safe administration of clinically indicated intravenous epoprostenol during pulmonary vasoreactivity testing.

Nicorandil attenuates monocrotaline-induced vascular endothelial damage and pulmonary arterial hypertension

Background

An antianginal K_ATP channel opener nicorandil has various beneficial effects on cardiovascular systems; however, its effects on pulmonary vasculature under pulmonary arterial hypertension (PAH) have not yet been elucidated. Therefore, we attempted to determine whether nicorandil can attenuate monocrotaline (MCT)-induced PAH in rats.

Materials and Methods

Sprague-Dawley rats injected intraperitoneally with 60 mg/kg MCT were randomized to receive either vehicle; nicorandil (5.0 mg·kg⁻¹·day⁻¹) alone; or nicorandil as well as either a K_ATP channel blocker glibenclamide or a nitric oxide synthase (NOS) inhibitor N^ω-nitro-l-arginine methyl ester (l-NAME), from immediately or 21 days after MCT injection. Four or five weeks later, right ventricular systolic pressure (RVSP) was measured, and lung tissue was harvested. Also, we evaluated the nicorandil-induced anti-apoptotic effects and activation status of several molecules in cell survival signaling pathway in vitro using human umbilical vein endothelial cells (HUVECs).

Results

Four weeks after MCT injection, RVSP was significantly increased in the vehicle-treated group (51.0±4.7 mm Hg), whereas it was attenuated by nicorandil treatment (33.2±3.9 mm Hg; P<0.01). Nicorandil protected pulmonary endothelium from the MCT-induced thromboemboli formation and induction of apoptosis, accompanied with both upregulation of endothelial NOS (eNOS) expression and downregulation of cleaved caspase-3 expression. Late treatment with nicorandil for the established PAH was also effective in suppressing the additional progression of PAH. These beneficial effects of nicorandil were blocked similarly by glibenclamide and l-NAME. Next, HUVECs were incubated in serum-free medium and then exhibited apoptotic morphology, while these changes were significantly attenuated by nicorandil administration. Nicorandil activated the phosphatidylinositol 3-kinase (PI3K)/Akt and extracellular signal-regulated kinase (ERK) pathways in HUVECs, accompanied with the upregulation of both eNOS and Bcl-2 expression.

Conclusions

Nicorandil attenuated MCT-induced vascular endothelial damage and PAH through production of eNOS and anti-apoptotic factors, suggesting that nicorandil might have a promising therapeutic potential for PAH.