World Health Organization group 5 pulmonary hypertension

Pharmacological Update and Emerging Treatments of Pulmonary Hypertension

Pulmonary hypertension (PH) is defined as elevated pressures in the pulmonary artery and is associated with significant morbidity and mortality. The World Health Organization classifies PH into 5 distinct groups based on underlying etiology, pathology, and modality of treatment. Therapeutic approach may be challenging due to the extensive spectrum of causes and underlying mechanisms mediating PH. The 5 groups include pulmonary arterial hypertension (group 1), PH secondary to left heart disease (group 2), PH secondary to chronic lung disease (group 3), chronic thromboembolic pulmonary hypertension (group 4), and PH due to miscellaneous causes (group 5). Although significant progress has been made in the treatment of group 1 PH, there is a continued need to develop new therapies for all types of PH. Additionally, most treatments currently available improve functional capacity and symptoms but without a significant benefit in mortality. In this review, we aim to describe the various etiologies of PH and their established pharmacotherapies, as well as expand on emerging therapeutic options for each group.

Pulmonary Hypertension in Chronic Lung Diseases: What Role Do Radiologists Play?

Pulmonary hypertension (PH) is a pathophysiological disorder, defined by a mean pulmonary arterial pressure (mPAP) > 20 mmHg at rest, as assessed by right heart catheterization (RHC). PH is not a specific disease, as it may be observed in multiple clinical conditions and may complicate a variety of thoracic diseases. Conditions associated with the risk of developing PH are categorized into five different groups, according to similar clinical presentations, pathological findings, hemodynamic characteristics, and treatment strategy. Most chronic lung diseases that may be complicated by PH belong to group 3 (interstitial lung diseases, chronic obstructive pulmonary disease, combined pulmonary fibrosis, and emphysema) and are associated with the lowest overall survival among all groups. However, some of the chronic pulmonary diseases may develop PH with unclear/multifactorial mechanisms and are included in group 5 PH (sarcoidosis, pulmonary Langerhans' cell histiocytosis, and neurofibromatosis type 1). This paper focuses on PH associated with chronic lung diseases, in which radiological imaging-particularly computed tomography (CT)-plays a crucial role in diagnosis and classification. Radiologists should become familiar with the hemodynamical, physiological, and radiological aspects of PH and chronic lung diseases in patients at risk of developing PH, whose prognosis and treatment depend on the underlying disease.

The role of NOX4 in pulmonary diseases

Nicotinamide adenine dinucleotide phosphate oxidase 4 (NOX4) is a subtype of the NOX family, which is mainly expressed in the pulmonary vasculature and pulmonary endothelial cells in the respiratory system. NOX4 has unique characteristics, and is a constitutively active enzyme that primarily produces hydrogen peroxide. The signaling pathways associated with NOX4 are complicated. Negative and positive feedback play significant roles in regulating NOX4 expression. The role of NOX4 is controversial because NOX4 plays a protective or damaging role in different respiratory diseases. This review summarizes the structure, enzymatic properties, regulation, and signaling pathways of NOX4. This review then introduces the roles of NOX4 in different diseases in the respiratory system, such as acute respiratory distress syndrome, chronic obstructive pulmonary disease, and pulmonary fibrosis.

Association of Disease Subtype and Duration with Echocardiographic Evidence of Pulmonary Hypertension in Myeloproliferative Neoplasm

BACKGROUND

Pulmonary hypertension (PH) can complicate the course of myeloproliferative neoplasms (MPNs). Echocardiography is a useful noninvasive screening test for PH in populations at risk. We aimed to investigate the echocardiographic evidence of PH and clinical characteristics of patients with MPNs.

METHODS

This study included 197 patients with MPNs (mean age, 59 ± 14 years; females, 53%; mean disease duration, 3.4 ± 2.8 years). Clinical and laboratory characteristics, including JAK2V617F mutation status, were obtained. All participants underwent a comprehensive transthoracic echocardiographic examination. The echocardiographic evidence of PH was defined as systolic pulmonary artery pressure (SPAP) ≥40 mm Hg.

RESULTS

Overall, 11 patients (5.5%) with SPAP ≥40 mm Hg had echocardiographic evidence of PH. Patients with myelofibrosis had echocardiographic evidence of PH more often than patients with other MPNs (p < 0.001). Disease duration since the diagnosis of MPNs was 6.7 ± 4.6 years in the PH group and 3.1 ± 2.5 years in the non-PH group (p < 0.001). There was a weak positive correlation between SPAP values and time since diagnosis (r = 0.236, p =0.001). JAK2V617F mutation was not associated with PH. In multivariate logistic regression analysis, the presence of myelofibrosis (odds ratio [OR]: 22.177, 95% CI: 4.480-109.790, p < 0.001), long disease duration (OR: 1.217, 95% CI: 1.024-1.447, p = 0.026), and high uric acid levels (OR: 1.868, 95% CI: 1.049-3.328, p = 0.034) were found to be related with the echocardiographic evidence of PH. Survival was worse in the PH group (p = 0.0001).

CONCLUSION

Our results suggest that patients with myelofibrosis are more likely to develop PH than other MPNs patients. Disease duration may predict the development of PH in MPN patients.

Lessons from lung transplantation: Cause for redefining the pathophysiology of pulmonary hypertension in gaucher disease

Background

Gaucher disease type 1 (GD1) is a lysosomal storage disease rarely resulting in end stage pulmonary hypertension (PH) and interstitial lung disease. There have only been two previous case reports of patients with GD1 receiving lung transplants.

Case presentation

We report a case of successful bilateral sequential lung transplantation in a patient with end-stage GD1-related PH. Prior to transplant, the patient was on enzyme replacement therapy with imiglucerase and pulmonary vasodilator therapy with bosentan, sildenafil and epoprostenol. The patient had pre-transplant comorbidities of prior splenectomy and osteopenia. She underwent bilateral sequential lung transplantation with basiliximab, methylprednisolone and mycophenolate mofetil induction. Her explanted lungs demonstrated severe pulmonary arterial hypertensive changes, but no Gaucher cells. She was maintained on MMF, tacrolimus, prednisone, imiglucerase and warfarin post-transplant. Her post-transplant course was complicated by hemorrhagic shock, prolonged support with extracorporeal membrane oxygenation, and acute renal failure requiring dialysis. Despite these complications, the patient was discharged and is doing well nine months post-transplantation.

Conclusions

This is one of only three reported cases of lung transplantation in patients with GD1. Each case has involved previously splenectomised, female patients with GD1. This is the first to report transplantation in a patient with severe PH and no pulmonary parenchymal disease. As evidenced in our patient, long term treatment with imiglucerase may eliminate the Gaucher cells in the lungs. The PH in these patients is most consistent with pulmonary arterial hypertension, raising the question of whether this should be reclassified as WHO Group 1 PH.

Morphometric Study of Pulmonary Arterial Changes in Pulmonary Langerhans Cell Histiocytosis

CONTEXT

- Pulmonary hypertension (PHT) is a complication of pulmonary Langerhans cell histiocytosis (PLCH); however, the pathogenesis remains largely unknown. Few studies have evaluated histopathologic changes in pulmonary arteries (PAs) of patients with PLCH; systematic quantification of arterial remodeling has yet to be undertaken.

OBJECTIVE

- To quantify the extent of arterial remodeling among patients with PLCH through morphometry and to correlate these results with pertinent clinical parameters.

DESIGN

- Patients with PLCH were identified from institutional files (1995-2015) along with age-, sex-, and smoking status-matched controls. Morphometric analysis of intimal and medial thickness of small to medium PAs was performed in patients with PLCH (within PLCH lesions [lesional] and away from PLCH lesions [nonlesional]) and controls. Paired measures were compared with Wilcoxon signed rank tests.

RESULTS

- Twenty-five patients with PLCH (14 men: median age, 46 years; interquartile range, 37-55 years) and 25 controls were included. The lesional arteries of patients with PLCH demonstrated thicker PA intima and media than controls ( P < .001 and P < .001, respectively), as did PLCH nonlesional arteries compared to controls ( P < .001 and P < .001, respectively). The PA intima and media were thicker within the PLCH lesions than nonlesional arteries ( P = .02 and P = .002, respectively). Patients with PLCH-related PHT had a worse prognosis than those without PHT ( P = .04; hazard ratio, 4.5 [1.1, 22.2]). Echocardiography parameters including right atrial size ( P = .007), estimated right atrial pressure ( P = .01), and right ventricular systolic pressure ( P = .01) were inversely associated with survival.

CONCLUSIONS

- Our findings suggest that factors other than direct vascular obstruction or inflammatory cell infiltration contribute, at least in part, to the vascular remodeling in PLCH.

Relationship between portopulmonary hypertension and splenectomy: Mayo Clinic experience and review of published works

AIM

Portopulmonary hypertension is a serious complication of portal hypertension that can lead to right heart failure and death. To our knowledge, an association between portopulmonary hypertension and prior splenectomy has not been described previously. The goals of this study were to describe the frequency of splenectomy in portopulmonary hypertension and compare selected parameters between portopulmonary hypertension subgroups.

METHODS

This is a retrospective analysis of patients diagnosed with portopulmonary hypertension between 1 January 1988 and 30 June 2015 at Mayo Clinic (Rochester, MN, USA). We compared age, sex, right ventricle systolic pressure by echocardiography, and right heart catheterization measurements/calculations among subgroups of portopulmonary hypertension patients with splenectomy and/or autoimmune liver disease (autoimmune hepatitis/primary biliary cirrhosis/primary sclerosing cholangitis).

RESULTS

The cohort consisted of 141 patients, of whom 8 (6%) had a history of splenectomy prior to the development of portopulmonary hypertension. Twenty-seven (19%) portopulmonary hypertension patients had autoimmune liver disease, and 5 of 8 (62.5%) splenectomized portopulmonary hypertension patients had autoimmune liver disease. No significant difference was noted in right heart catheterization measurements/calculations between splenectomized and non-splenectomized portopulmonary hypertension patients. Right ventricle systolic pressure by echocardiography was significantly higher in those splenectomized.

CONCLUSIONS

Prior history of splenectomy in portopulmonary hypertension was 6% in this cohort. The combination of autoimmune liver disease and splenectomy in portopulmonary hypertension was not uncommon. History of splenectomy in patients with portal hypertension and/or autoimmune liver disease may have clinical implications.

Medical Management of Pulmonary Hypertension with Unclear and/or Multifactorial Mechanisms (Group 5): Is There a Role for Pulmonary Arterial Hypertension Medications?

PURPOSE OF REVIEW

The purpose of this review was to outline the mechanisms and to review recent literature on pulmonary arterial hypertension (PAH) medications in group 5 pulmonary hypertension (PH).

RECENT FINDINGS

The first steps in management are to understand the mechanisms and hemodynamic profile and to exclude chronic thromboembolic disease. Recent studies in the past 5 years have found that PAH medications may improve hemodynamics in patients with pre-capillary pulmonary hypertension due to sarcoidosis, pulmonary Langerhans cell histiocytosis, lymphangioleiomyomatosis, and myeloproliferative disorders with dasatinib-induced PH. Improvements in exercise capacity are uncommon, and no survival benefit has been demonstrated. There is a risk of pulmonary edema in patients with pulmonary venous involvement or fibrosing mediastinitis when treated with PAH therapies. There is limited evidence supporting the use of PAH medications in group 5 patients, and they may be harmful in certain cases. In most patients with group 5 PH, treatment should be directed to the underlying disease with PAH therapies reserved for patients with severe pre-capillary PH.

Pulmonary extra-medullary hematopoiesis and pulmonary hypertension from underlying polycythemia vera: a case series

Myeloproliferative neoplasia (MPN)-associated pulmonary hypertension (PH) is included in group five of the most recent clinical classification of PH.¹ The MPNs are a heterogeneous group of disorders that includes disorders with primary expression of a myeloid phenotype and disorders characterized by expression of the Janus Kinase 2 (JAK2) mutation, p.V617F. The latter includes essential thrombocytosis, polycythemia vera, and idiopathic myelofibrosis.² Pulmonary extra-medullary hematopoiesis (EMH) refers to the presence of hematopoietic precursor cells in the lung. It is a rare complication associated with myelofibrosis. Here we present a case series highlighting the clinical–pathological–radiological features of pulmonary EMH and PH from underlying polycythemia vera.

Pulmonary Langerhans Cell Histiocytosis: An Update From the Pathologists' Perspective

CONTEXT

Pulmonary Langerhans cell histiocytosis (PLCH) is a rare histiocytic disorder that almost exclusively affects the lungs of smokers. PLCH is characterized by bronchiolocentric nodules and/or cysts in an upper and mid lung distribution with sparing of the costophrenic angles. The diagnosis can be challenging and often requires transbronchial biopsy or surgical lung biopsy. Pulmonary hypertension is a relatively common and sometimes severe complication of PLCH. The pathogenesis of PLCH is still debated. Recently, BRAF V600E mutation and BRAF expression have been identified in some patients with PLCH, suggesting that at least a subset of PLCH has a clonal proliferation. While smoking cessation is the first-line treatment of PLCH, some patients might require additional treatment and eventually transplant. Given that the lesional cells of PLCH express BRAF in some patients, MAPKinase pathway-targeted treatment might be useful for therapy-resistant patients.

OBJECTIVE

To present the more recently recognized clinical and pathologic aspects of PLCH, including pulmonary hypertension in PLCH, pathogenesis, and treatment, as well as the basic diagnostic approach to PLCH.

DATA SOURCES

Authors' own research, and search of literature database (PubMed) and UpToDate.

CONCLUSIONS

Despite the recent progress, more studies are needed to elucidate the biology of PLCH for identification of prognostic factors and appropriate treatment options, especially for therapy-refractory PLCH cases.

Statement on pregnancy in pulmonary hypertension from the Pulmonary Vascular Research Institute

Pregnancy outcomes in patients with pulmonary hypertension remain poor despite advanced therapies. Although consensus guidelines recommend against pregnancy in pulmonary hypertension, it may nonetheless occasionally occur. This guideline document sought to discuss the state of knowledge of pregnancy effects on pulmonary vascular disease and to define usual practice in avoidance of pregnancy and pregnancy management. This guideline is based on systematic review of peer-reviewed, published literature identified with MEDLINE. The strength of the literature was graded, and when it was inadequate to support high-level recommendations, consensus-based recommendations were formed according to prespecified criteria. There was no literature that met standards for high-level recommendations for pregnancy management in pulmonary hypertension. We drafted 38 consensus-based recommendations on pregnancy avoidance and management. Further, we identified the current state of knowledge on the effects of sex hormones during pregnancy on the pulmonary vasculature and right heart and suggested areas for future study. There is currently limited evidence-based knowledge about both the basic molecular effects of sex hormones and pregnancy on the pulmonary vasculature and the best practices in contraception and pregnancy management in pulmonary hypertension. We have drafted 38 consensus-based recommendations to guide clinicians in these challenging topics, but further research is needed in this area to define best practices and improve patient outcomes.

Sarcoidosis-associated pulmonary hypertension and lung transplantation for sarcoidosis

Pulmonary hypertension (PH) is a significant complication of sarcoidosis, occurring in approximately 6 to > 20% of cases, and markedly increases mortality among these patients. The clinician should exercise a high index of suspicion for sarcoidosis-associated PH (SAPH) given the nonspecific symptomatology and the limitations of echocardiography in this patient population. The pathophysiology of PH in sarcoidosis is complex and multifactorial. Importantly, there are inherent differences in the pathogenesis of SAPH compared with idiopathic pulmonary arterial hypertension, making the optimal management of SAPH controversial. In this article, we review the epidemiology, diagnosis, prognosis, and treatment considerations for SAPH. Lung transplantation (LT) is a viable therapeutic option for sarcoid patients with severe pulmonary fibrocystic sarcoidosis or SAPH refractory to medical therapy. We discuss the role for LT in patients with sarcoidosis, review the global experience with LT in this population, and discuss indications and contraindications to LT.