Sonja Bartolome

Portopulmonary hypertension: An update

Portopulmonary hypertension (POPH) is a serious complication of cirrhosis that is associated with mortality beyond that predicted by the Model for End‐Stage Liver Disease (MELD) score. Increased pulmonary vascular resistance (PVR) may be initiated by pulmonary vasoconstriction, altered levels of circulating mediators, or shear stress, and can eventually lead to the classic vascular remodeling (plexiform lesion) that characterizes POPH. Portal hypertension is a prerequisite for the diagnosis of POPH, although the severity of pulmonary hypertension is unrelated to the severity of portal hypertension or the nature or severity of liver disease. POPH precludes liver transplantation (LT) unless the mean pulmonary artery pressure (MPAP) can be reduced to a safe level. The concept of an acceptable pressure has changed: we now consider both MPAP and PVR in the diagnosis, and we include the transpulmonary pressure gradient so that we can factor in fluid overload and left ventricular failure. Pulmonary vasodilator therapy includes oral, inhaled, and parenteral agents, and one or more of these agents may significantly lower pulmonary artery pressures to the point that LT becomes possible. The United Network for Organ Sharing recommends MELD exception points for patients with medically controlled POPH, but this varies by region. Patients who undergo LT need specialized intraoperative and postoperative management, which includes the availability of intraoperative transesophageal echocardiography for assessing right ventricular function, and rapidly acting vasodilators (eg, inhaled nitric oxide and/or epoprostenol). Published case series suggest excellent outcomes after LT for patients who respond to medical therapy. Liver Transpl , 2012.

Hypoxia-inducible factor-1 α/platelet derived growth factor axis in HIV-associated pulmonary vascular remodeling

BackgroundHuman immunodeficiency virus (HIV) infected patients are at increased risk for the development of pulmonary arterial hypertension (PAH). Recent reports have demonstrated that HIV associated viral proteins induce reactive oxygen species (ROS) with resultant endothelial cell dysfunction and related vascular injury. In this study, we explored the impact of HIV protein induced oxidative stress on production of hypoxia inducible factor (HIF)-1α and platelet-derived growth factor (PDGF), critical mediators implicated in the pathogenesis of HIV-PAH.MethodsThe lungs from 4-5 months old HIV-1 transgenic (Tg) rats were assessed for the presence of pulmonary vascular remodeling and HIF-1α/PDGF-BB expression in comparison with wild type controls. Human primary pulmonary arterial endothelial cells (HPAEC) were treated with HIV-associated proteins in the presence or absence of pretreatment with antioxidants, for 24 hrs followed by estimation of ROS levels and western blot analysis of HIF-1α or PDGF-BB.ResultsHIV-Tg rats, a model with marked viral protein induced vascular oxidative stress in the absence of active HIV-1 replication demonstrated significant medial thickening of pulmonary vessels and increased right ventricular mass compared to wild-type controls, with increased expression of HIF-1α and PDGF-BB in HIV-Tg rats. The up-regulation of both HIF-1α and PDGF-B chain mRNA in each HIV-Tg rat was directly correlated with an increase in right ventricular/left ventricular+septum ratio. Supporting our in-vivo findings, HPAECs treated with HIV-proteins: Tat and gp120, demonstrated increased ROS and parallel increase of PDGF-BB expression with the maximum induction observed on treatment with R5 type gp-120CM. Pre-treatment of endothelial cells with antioxidants or transfection of cells with HIF-1α small interfering RNA resulted in abrogation of gp-120CM mediated induction of PDGF-BB, therefore, confirming that ROS generation and activation of HIF-1α plays critical role in gp120 mediated up-regulation of PDGF-BB.ConclusionIn summary, these findings indicate that viral protein induced oxidative stress results in HIF-1α dependent up-regulation of PDGF-BB and suggests the possible involvement of this pathway in the development of HIV-PAH.

Risk assessment in pulmonary hypertension associated with heart failure and preserved ejection fraction

BACKGROUND Pulmonary hypertension (PH) is common in patients with left heart failure (HF), especially those with HF and preserved ejection fraction (HFpEF). However, there is limited data on risk stratification in these patients. METHODS Baseline clinical and hemodynamic variables of 339 patients with World Health Organization (WHO) Group 2 PH, 90% of whom had HFpEF, were studied to derive a multivariate Cox proportional hazards model. A simplified prognostic risk score was created based on the outcome of all-cause mortality. Nine predictors, significant after stepwise multivariable regression (p < 0.05), were used to create the risk score. Components of the risk score were functional class, diastolic blood pressure, pulmonary artery saturation, interstitial lung disease, hypotension on initial presentation, right ventricular hypertrophy, diffusion capacity of the lung for carbon monoxide, and 2 serum creatinine variables (≤ 0.9 mg/dl and ≥ 1.4 mg/dl). RESULTS Overall 2-year survival was 73.8% ± 2.4% in the derivation cohort, and 87.5% ± 2.3%, 66.4% ± 4.9%, and 24.4% ± 6.7% for risk scores of 0 to 2, 3 to 4, and 5+, respectively (p < 0.0001 for the trend), with a C-index of 0.76 (95% confidence interval [CI], 0.71-0.81). The risk score was validated in 2 independent PH-HFpEF cohorts: 179 patients with a C-index of 0.68 (95% CI, 0.55-0.80) and 117 patients with a C-index of 0.68 (95% CI, 0.53-0.83). For the 3 cohorts combined (N = 635), the overall C-index was 0.72 (95% CI 0.68-0.76). In all 3 cohorts individually and in the 3 cohorts combined, the risk score predicted death (hazard ratio, 1.4-1.6; p < 0.01). CONCLUSIONS Several clinical factors independently predict death in PH-HFpEF confirmed by validation. A novel risk score composed of these factors can be used to determine prognosis and may be useful in making therapeutic decisions.

Deferoxamine mimics the pattern of hypoxia-related injury at the microvasculature

Oxygen is essential for the maintenance of life, and when oxygen levels decline to critical levels, a program of complex mechanisms exists to i) sense hypoxia, ii) respond to minimize acute tissue injury, and iii) result in adaptations that offer protection against further hypoxia challenges. Alternative adaptation-related protection may also be inducible through the increased activity of hypoxia-inducible factors activated by hypoxia mimics such as iron chelation with deferoxamine (DFA). We have characterized a set of hypoxia-related responses at the microvasculature and postulated that microvascular injury in response to hypoxia could be reproduced by the reduction of bioavailable iron through chelation by DFA. We were able to induce a similar degree of leukocyte adherence and emigration and vascular leak with DFA infusion as compared with hypoxia exposure in an intact physiological rodent model. However, in contrast to hypoxia-exposed groups, we were unable to detect reactive oxygen species or alter the injury pattern with reactive oxygen species scavenger in the groups treated with DFA. Thus, we demonstrate that DFA mimics the pattern and intensity of hypoxia-related injury on the microvasculature; however, differences in the time course and mechanism of injury were identified. In addition, DFA saturated with iron did not completely reverse the effects of DFA, suggesting a mechanism(s) beyond a reduction in the bioavailability of iron. These findings may have importance in the targeting of iron for the development of hypoxia mimics that may offer protection against subsequent hypoxia exposure in clinical setting such as myocardial infarction and stroke.

Long-term therapy with oral treprostinil in pulmonary arterial hypertension failed to lead to improvement in important physiologic measures: results from a single center

Sustained-release oral treprostinil, an oral prostacyclin, led to significant improvement in 6-minute walk distance (6MWD) versus placebo in treatment-naive patients with pulmonary arterial hypertension (PAH) but failed to lead to significant improvement in two 16-week trials in patients receiving background PAH therapies (FREEDOM studies). Long-term studies are lacking. Our objective was to evaluate 6MWD, functional class, hemodynamics, and other long-term outcomes during oral treprostinil administration in PAH. Patients receiving oral treprostinil through the FREEDOM studies at our institution were included and were followed for up to 7 years. The primary end point was change in pulmonary vascular resistance (PVR) at first follow-up catheterization. Other end points included 6MWD, functional class, and other hemodynamic results. Thirty-seven patients received oral treprostinil for a median of 948 days, with 81%, 61%, and 47% continuing therapy at 1, 2, and 3 years, respectively. Mean treprostinil dose at 3, 12, and 24 months was 4.3 ± 2.3, 8.6 ± 3.2, and 11.7 ± 5.8 mg/24 h, respectively. Compared with pretreatment values, there was no significant change in 6MWD at 3 or 12 months, no improvement in functional class at 12 months, and no significant change in hemodynamics at the first follow-up catheterization (N = 34). Oral treprostinil dose was inversely associated with change in PVR (r = −0.42, P < 0.05), and change in PVR was numerically better among patients in the highest dosing quartile. No significant improvement in 6MWD, functional class, or hemodynamics versus pretreatment values was seen with long-term oral treprostinil therapy, potentially because of inability to achieve a clinically effective dose.

Pulmonary Hypertension in Parenchymal Lung Disease

The pathophysiology of pulmonary hypertension (PH) in parenchymal lung diseases is partially related to hypoxic pulmonary vasoconstriction. PH treatment is controversial for these patients. This article focuses on group III PH, namely PH attributable to lung diseases and/or hypoxia. Group III includes chronic obstructive pulmonary disease and interstitial lung diseases, the most common parenchymal lung diseases associated with PH. It also includes sleep-disordered breathing and hypoventilation from any cause. Other parenchymal lung diseases associated with PH, namely sarcoidosis and systemic vasculitides (group V), are discussed. The data describing PH in specific parenchymal diseases are reviewed.

Inflammatory bowel diseases, chronic liver diseases, and the lung

This review is devoted to the distinct associations of inflammatory bowel diseases (IBD) and chronic liver disorders with chronic airway diseases, namely chronic obstructive pulmonary disease and bronchial asthma, and other chronic respiratory disorders in the adult population. While there is strong evidence for the association of chronic airway diseases with IBD, the data are much weaker for the interplay between lung and liver multimorbidities. The association of IBD, encompassing Crohns disease and ulcerative colitis, with pulmonary disorders is underlined by their heterogeneous respiratory manifestations and impact on chronic airway diseases. The potential relationship between the two most prevalent liver-induced pulmonary vascular entities, i.e. portopulmonary hypertension and hepatopulmonary syndrome, and also between liver disease and other chronic respiratory diseases is also approached. Abnormal lung function tests in liver diseases are described and the role of increased serum bilirubin levels on chronic respiratory problems are considered. Lung–gut cross-talk: the association of IBD with respiratory multimorbitidies, including COPD and bronchial asthma http://ow.ly/UT94a

Does Treatment Response to Ambrisentan Vary by Pulmonary Arterial Hypertension Severity? Implications for Clinicians and for the Design of Future Clinical Trials

Recent clinical trials in pulmonary arterial hypertension have included World Health Organization functional classes I and II patients. However, the impact of baseline functional class and other measures of severity on outcomes has not been evaluated in detail.

Predictors of Waitlist Mortality in Portopulmonary Hypertension

Background The current Organ Procurement Transplantation Network policy grants Model for End-Stage Liver Disease (MELD) exception points to patients with portopulmonary hypertension (POPH), but potentially important factors, such as severity of liver disease and pulmonary hypertension, are not included in the exception score, and may affect survival. The purpose of this study was to identify significant predictors of waitlist mortality in patients with POPH. Methods We performed a retrospective cohort study of patients in the Organ Procurement and Transplantation Network database with hemodynamics consistent with POPH (defined as mean pulmonary arterial pressure >25 mm Hg and pulmonary vascular resistance [PVR] ≥240 dynes·s·cm−5) who were approved for a POPH MELD exception between 2006 and 2014. Using a Cox proportional hazards model, we identified predictors of waitlist mortality (or removal for clinical deterioration). Results One hundred ninety adults were included. Age (hazard ratio [HR], 1.04; 95% confidence interval [CI], 1.00-1.08; P = 0.0499), initial native MELD score (HR, 1.11; 95% CI, 1.05-1.17; P < 0.001), and initial PVR (HR, 1.12 per 100 dynes·s·cm−5; 95% CI, 1.02-1.23; P = 0.02) were the only significant univariate predictors of waitlist mortality and remained significant predictors in a multivariate model, which had a c-statistic of 0.71. PVR and mean pulmonary arterial pressure were not significant predictors of posttransplant mortality. Conclusions Both the severity of liver disease and POPH (as assessed by MELD and PVR, respectively) were significantly associated with waitlist, but not posttransplant, mortality in patients with approved MELD exceptions for POPH. Both factors should potentially be included in the POPH MELD exception score to more accurately reflect waitlist mortality risk.

Clinical advances in pulmonary arterial hypertension: the year in review

Purpose of review The purpose of this review is to summarize the last year of literature developments in the field of pulmonary arterial hypertension (PAH), with a focus on clinical research. Recent findings Pulmonary vascular research has expanded rapidly over the last decade, resulting in a change in the treatment strategy for PAH. Epidemiologic data from recent registries suggest that patients with PAH are increasing in age and comorbidities. In the modern treatment era, risk stratification for early mortality is increasingly used to guide clinicians in the choice of pulmonary vasodilator therapy. Risk-score calculators have been published and validated for PAH, currently in both the United States and Europe. In addition to increased comorbidities, pulmonary hypertension centers are encountering complicated management situations in these patients, such as pregnancy. Current data suggest that mortality for pregnant pulmonary hypertension patients remains high, although not as high as historical reports. Oral prostacyclin and prostacyclin agonist therapies are currently under investigation to aid in the management of these patients. Summary Despite treatment advances, mortality remains high for PAH patients. Careful evaluation and risk stratification will help guide the appropriate treatment for PAH patients. Additional therapies are on the horizon for the management of this progressive disease.