Progressive Pulmonary Arterial Hypertension Research Articles

Mitochondria as a primary determinant of angiogenic modality in pulmonary arterial hypertension.

Impaired pulmonary angiogenesis plays a pivotal role in the progression of pulmonary arterial hypertension (PAH) and patient mortality, yet the molecular mechanisms driving this process remain enigmatic. Our study uncovered a striking connection between mitochondrial dysfunction (MD), caused by a humanized mutation in the NFU1 gene, and severely disrupted pulmonary angiogenesis in adult lungs. Restoring the bioavailability of the NFU1 downstream target, lipoic acid (LA), alleviated MD and angiogenic deficiency and rescued the progressive PAH phenotype in the NFU1G206C model. Notably, significant NFU1 expression and signaling insufficiencies were also identified in idiopathic PAH (iPAH) patients' lungs, emphasizing this study's relevance beyond NFU1 mutation cases. The remarkable improvement in mitochondrial function of PAH patient-derived pulmonary artery endothelial cells (PAECs) following LA supplementation introduces LA as a potential therapeutic approach. In conclusion, this study unveils a novel role for MD in dysregulated pulmonary angiogenesis and PAH manifestation, emphasizing the need to correct MD in PAH patients with unrecognized NFU1/LA deficiency.

Novel Hemodynamic, Vascular Lesion, and Cytokine/Chemokine Differences Regarding Sex in a Pulmonary Arterial Hypertension Model.

Sex differences are recognized in pulmonary hypertension. However, the progression of disease with regard to vascular lesion formation and circulating cytokines/chemokines is unknown. To determine whether vascular lesion formation, changes in hemodynamics, and alterations in circulating chemokines/cytokines differ between males and females, we used a progressive model of pulmonary arterial hypertension (PAH), Sugen/hypoxia, and analyzed cohorts of male and female rats at time points suggested to indicate worsening disease. Our analysis included echocardiography for hemodynamics, morphometry, immunofluoresecence, and chemokine/cytokine analysis of plasma at each time point in both sexes. We found that male rats had significantly increased Fulton index, compared with those for females at each time point, as well as increased medial artery thickening at 8 weeks of PAH. Furthermore, females exhibited fewer obliterative vascular lesions than males at our latest time point. Our data also show increased IL-4, granulocyte-macrophage colony-stimulating factor, IL-10, and macrophage interacting protein-1α that were not observed in females, whereas females were observed to have increased RANTES (whose name derives from Regulated upon Activation, Normal T Cell Expressed and Presumably Secreted) and CXCL-10 that were not found in males. Males also have increased infiltrating macrophages in vascular lesions, compared with females. We found that development of progressive PAH in hemodynamics, morphology, and chemokine/cytokine circulation differs significantly between males and females. These data suggest a macrophage-driven pathology in males, whereas there may be T cell protection from vascular damage in females with PAH.

Long-Term Safety, Outcome, and Clinical Effects of Subcutaneous and Intravenous Treprostinil Treatment in Patients with Severe Chronic Pulmonary Arterial Hypertension

Background: Current guidelines recommend treatment with parenteral prostacyclin analogs in patients with severe pulmonary arterial hypertension (PAH), who have insufficient response to treatment. Real-life data are sought to help physicians in treatment decisions and clinical care of patients. Objective: This study analyzed safety, clinical effects, and long-term outcomes of subcutaneous (sc) and/or intravenous (iv) treprostinil via different pump systems in consecutive patients with PAH. Methods: Thirty-seven patients with severe progressive PAH despite dual combination therapy (20 female, mean age: 52.3 ± 15 years, mean pulmonary vascular resistance: 12.1 ± 5.1 WU) were initiated with add-on treprostinil sc and were routinely clinically assessed. Changes in clinical parameters, adverse events, and outcome were analyzed retrospectively. Results: In 24 of 37 patients, treprostinil administration was continued iv via implantation of LENUS Pro® pump after 3 ± 1.3 months, 6 patients continued with sc therapy, and 7 discontinued treatment. After 3, 6, 9, and 12 months of treprostinil treatment, patients showed a significant improvement in mean 6-min walk distance and tricuspid annular plane systolic excursion compared to baseline. In 8 of the 24 patients, iv pumps required surgical revision. During a mean follow-up of 2.82 ± 1.95 years, 12 patients died, four received lung transplantation. Transplant-free survival after 1, 2, and 3 years was 85.7%, 69.2%, and 65.3%, respectively. Conclusion: sc treprostinil as add-on to double combination treatment significantly improved exercise capacity and right heart function. In most patients, treprostinil could be continued via more tolerable iv administration approach (LENUS Pro® pump), showing reasonable overall survival with respect to the severity of PAH.

The Evolving Management and Treatment Options for Patients with Pulmonary Hypertension: Current Evidence and Challenges.

Pulmonary hypertension may develop as a disease process specific to pulmonary arteries with no identifiable cause or may occur in relation to other cardiopulmonary and systemic illnesses. The World Health Organization (WHO) classifies pulmonary hypertensive diseases on the basis of primary mechanisms causing increased pulmonary vascular resistance. Effective management of pulmonary hypertension begins with accurately diagnosing and classifying the disease in order to determine appropriate treatment. Pulmonary arterial hypertension (PAH) is a particularly challenging form of pulmonary hypertension as it involves a progressive, hyperproliferative arterial process that leads to right heart failure and death if untreated. Over the last two decades, our understanding of the pathobiology and genetics behind PAH has evolved and led to the development of several targeted disease modifiers that ameliorate hemodynamics and quality of life. Effective risk management strategies and more aggressive treatment protocols have also allowed better outcomes for patients with PAH. For those patients who experience progressive PAH with medical therapy, lung transplantation remains a life-saving option. More recent work has been directed at developing effective treatment strategies for other forms of pulmonary hypertension, such as chronic thromboembolic pulmonary hypertension (CTEPH) and pulmonary hypertension due to other lung or heart diseases. The discovery of new disease pathways and modifiers affecting the pulmonary circulation is an ongoing area of intense investigation.

Echocardiographic, Biochemical, and Electrocardiographic Correlates Associated With Progressive Pulmonary Arterial Hypertension.

Background: Pulmonary arterial hypertension (PAH) is a progressive proliferative vasculopathy associated with mechanical and electrical changes, culminating in increased vascular resistance, right ventricular (RV) failure, and death. With a main focus on invasive tools, there has been an underutilization of echocardiography, electrocardiography, and biomarkers to non-invasively assess the changes in myocardial and pulmonary vascular structure and function during the course of PAH.Methods: A SU5416-hypoxia rat model was used for inducing PAH. Biventricular functions were measured using transthoracic two-dimensional (2D) echocardiography/Doppler (echo/Doppler) at disease onset (0 week), during progression (3 weeks), and establishment (5 weeks). Similarly, electrocardiography was performed at 0, 3, and 5 weeks. Invasive hemodynamic measurements and markers of cardiac injury in plasma were assessed at 0, 3, and 5 weeks.Results: Increased RV systolic pressure (RVSP) and rate of isovolumic pressure rise and decline were observed at 0, 3, and 5 weeks in PAH animals. EKG showed a steady increase in QT-interval with progression of PAH, whereas P-wave height and RS width were increased only during the initial stages of PAH progression. Echocardiographic markers of PAH progression and severity were also identified. Three echocardiographic patterns were observed: a steady pattern (0–5 weeks) in which echo parameter changed progressively with severity [inferior vena cava (IVC) expiratory diameter and pulmonary artery acceleration time (PAAT)], an early pattern (0–3 weeks) where there is an early change in parameters [RV fractional area change (RV-FAC), transmitral flow, left ventricle (LV) output, estimated mean PA pressure, RV performance index, and LV systolic eccentricity index], and a late pattern (3–5 weeks) in which there is only a late rise at advanced stages of PAH (LV diastolic eccentricity index). RVSP correlated with PAAT, PAAT/PA ejection times, IVC diameters, RV-FAC, tricuspid systolic excursion, LV systolic eccentricity and output, and transmitral flow. Plasma myosin light chain (Myl-3) and cardiac troponin I (cTnI) increased progressively across the three time points. Cardiac troponin T (cTnT) and fatty acid-binding protein-3 (FABP-3) were significantly elevated only at the 5-week time point.Conclusion: Distinct electrocardiographic and echocardiographic patterns along with plasma biomarkers were identified as useful non-invasive tools for monitoring PAH progression.

Where the congenital heart disease meets the pulmonary arterial hypertension, FLNA matters: a case report and literature review

BackgroundPediatric patients with genetic disorders have a higher incidence of pulmonary arterial hypertension (PAH) regardless of their heart defects. Filamin A (FLNA) mutation is recently recognized to be associated with pediatric pulmonary disorders, however, the clinical courses of PAH related to the mutation were reported in limited cases. Here, we presented a case and pooled data for better understanding of the correlation between FLNA mutation and pediatric PAH.Case presentationThe patient was a 8-month-old female with repeated episodes of pneumonia. Physical examination revealed cleft lip, cleft palate and developmental retardation. Imaging examination showed a small atrial septal defect (ASD), central pulmonary artery enlargement, left upper lobe of lung atelectasis, and pulmonary infiltration. Genetic test showed she carried a de novo pathogenic variant of FLNA gene (c.5417-1G > A, p.-). Oral medications didn’t slow the progression of PAH in the patient, and she died two years later.ConclusionsFLNA mutation causes rare but progressive PAH in addition to a wide spectrum of congenital heart disease and other comorbidities in pediatric patients. We highly recommend genetic testing for pediatric patients when suspected with PAH. Given the high mortality in this group, lung transplantation may offer a better outcome.

Necrosis-Released HMGB1 (High Mobility Group Box 1) in the Progressive Pulmonary Arterial Hypertension Associated With Male Sex.

Damage-associated molecular patterns, such as HMGB1 (high mobility group box 1), play a well-recognized role in the development of pulmonary arterial hypertension (PAH), a progressive fatal disease of the pulmonary vasculature. However, the contribution of the particular type of vascular cells, type of cell death, or the form of released HMGB1 in PAH remains unclear. Moreover, although male patients with PAH show a higher level of circulating HMGB1, its involvement in the severe PAH phenotype reported in males is unknown. In this study, we aimed to investigate the sources and active forms of HMGB1 released from damaged vascular cells and their contribution to the progressive type of PAH in males. Our results showed that HMGB1 is released by either pulmonary artery human endothelial cells or human pulmonary artery smooth muscle cells that underwent necrotic cell death, although only human pulmonary artery smooth muscle cells produce HMGB1 during apoptosis. Moreover, only human pulmonary artery smooth muscle cell death induced a release of dimeric HMGB1, found to be mitochondrial reactive oxygen species dependent, and TLR4 (toll-like receptor 4) activation. The modified Sugen/Hypoxia rat model replicates the human sexual dimorphism in PAH severity (right ventricle systolic pressure in males versus females 54.7±2.3 versus 44.6±2 mm Hg). By using this model, we confirmed that necroptosis and necrosis are the primary sources of circulating HMGB1 in the male rats, although only necrosis increased circulation of HMGB1 dimers. Attenuation of necrosis but not apoptosis or necroptosis prevented TLR4 activation in males and blunted the sex differences in PAH severity. We conclude that necrosis, through the release of HMGB1 dimers, predisposes males to a progressive form of PAH.

Multiscale Modeling Framework of Ventricular-Arterial Bi-directional Interactions in the Cardiopulmonary Circulation.

Ventricular-arterial coupling plays a key role in the physiologic function of the cardiovascular system. We have previously described a hybrid lumped-finite element (FE) modeling framework of the systemic circulation that couples idealized FE models of the aorta and the left ventricle (LV). Here, we describe an extension of the lumped-FE modeling framework that couples patient-specific FE models of the left and right ventricles, aorta and the large pulmonary arteries in both the systemic and pulmonary circulations. Geometries of the FE models were reconstructed from magnetic resonance (MR) images acquired in a pediatric patient diagnosed with pulmonary arterial hypertension (PAH). The modeling framework was calibrated with pressure waveforms acquired in the heart and arteries by catheterization as well as ventricular volume and arterial diameter waveforms measured from MR images. The calibrated model hemodynamic results match well with the clinically-measured waveforms (volume and pressure) in the LV and right ventricle (RV) as well as with the clinically-measured waveforms (pressure and diameter) in the aorta and main pulmonary artery. The calibrated framework was then used to simulate three cases, namely, (1) an increase in collagen in the large pulmonary arteries, (2) a decrease in RV contractility, and (3) an increase in the total pulmonary arterial resistance, all characteristics of progressive PAH. The key finding from these simulations is that hemodynamics of the pulmonary vasculature and RV wall stress are more sensitive to vasoconstriction with a 10% of reduction in the lumen diameter of the distal vessels than a 67% increase in the proximal vessel's collagen mass.

Comparison of Outcomes of Living-Donor Lobar and Cadaveric Lung Transplantation in Patients with Pulmonary Arterial Hypertension

Purpose Lung transplantation is indicated in patients with severe pulmonary arterial hypertension (PAH). Living donor lobar lung transplantation (LDLLT) may be considered in patients who might not survive the longer waiting duration for cadaveric lung transplantation (CLT). This study compared the outcomes of LDLLT and CLT in patients with PAH. Methods Retrospective review of medical records from our institutional database between April 2008 and August 2018 revealed 191 lung transplants, of which 6 LDLLTs and 10 CLTs were performed for PAH patients, defined based on the criteria for group 1 of the Nice classification. Results Preoperatively, LDLLT and CLT groups showed no significant differences in age (median 14 vs. 29.5 years, p=0.08), height (median 155 vs. 160 cm, p=0.91), mean pulmonary arterial pressure (PAP) (median 60.5 vs. 57.0 mmHg, p=0.96), brain natriuretic peptide (median 153 vs. 89.0 pg/mL, p=0.36), and dose of intravenous epoprostenol (median 29.7 vs. 65.2 ng/kg/min, p=0.55). All cases of LDLLT were bilateral, except one performed in a pediatric patient. In 2 cases, bilateral LDLLTs were performed by preserving the upper lobes for size mismatch. After surgery, extracorporeal cardiopulmonary support was required in 5 LDLLT cases and 4 CLT cases (p= 0.384). One hospital death occured on day 192 due to sepsis in the CLT group. The median postoperative PAP was 16.5 mmHg and 14.0 mmHg (p=0.213) and the ratio between the pre- and postoperative mean PAP were 26.6% and 26.4% (p=0.456) in the LDLLT and CLT groups, respectively. The median follow-up period was 57.5 and 22.5 months and the five-year survival was 100% and 88.9% (p=0.41) in LDLLT and CLT groups, respectively. Conclusion LDLLTs were associated with acceptable outcomes in patients with PAH and were not inferior to CLTs. Thus, for patients with severe progressive PAH, LDLLTs may be a lifesaving procedure. Lung transplantation is indicated in patients with severe pulmonary arterial hypertension (PAH). Living donor lobar lung transplantation (LDLLT) may be considered in patients who might not survive the longer waiting duration for cadaveric lung transplantation (CLT). This study compared the outcomes of LDLLT and CLT in patients with PAH. Retrospective review of medical records from our institutional database between April 2008 and August 2018 revealed 191 lung transplants, of which 6 LDLLTs and 10 CLTs were performed for PAH patients, defined based on the criteria for group 1 of the Nice classification. Preoperatively, LDLLT and CLT groups showed no significant differences in age (median 14 vs. 29.5 years, p=0.08), height (median 155 vs. 160 cm, p=0.91), mean pulmonary arterial pressure (PAP) (median 60.5 vs. 57.0 mmHg, p=0.96), brain natriuretic peptide (median 153 vs. 89.0 pg/mL, p=0.36), and dose of intravenous epoprostenol (median 29.7 vs. 65.2 ng/kg/min, p=0.55). All cases of LDLLT were bilateral, except one performed in a pediatric patient. In 2 cases, bilateral LDLLTs were performed by preserving the upper lobes for size mismatch. After surgery, extracorporeal cardiopulmonary support was required in 5 LDLLT cases and 4 CLT cases (p= 0.384). One hospital death occured on day 192 due to sepsis in the CLT group. The median postoperative PAP was 16.5 mmHg and 14.0 mmHg (p=0.213) and the ratio between the pre- and postoperative mean PAP were 26.6% and 26.4% (p=0.456) in the LDLLT and CLT groups, respectively. The median follow-up period was 57.5 and 22.5 months and the five-year survival was 100% and 88.9% (p=0.41) in LDLLT and CLT groups, respectively. LDLLTs were associated with acceptable outcomes in patients with PAH and were not inferior to CLTs. Thus, for patients with severe progressive PAH, LDLLTs may be a lifesaving procedure.

Inositol monophosphatase 1 as a novel interacting partner of RAGE in pulmonary hypertension.

Pulmonary arterial hypertension (PAH) is a lethal disease characterized by progressive pulmonary vascular remodeling. The receptor for advanced glycation end products (RAGE) plays an important role in PAH by promoting proliferation of pulmonary vascular cells. RAGE is also known to mediate activation of Akt signaling, although the particular molecular mechanism remains unknown. This study aimed to identify the interacting partner of RAGE that could facilitate RAGE-mediated Akt activation and vascular remodeling in PAH. The progressive angioproliferative PAH was induced in 24 female Sprague-Dawley rats ( n = 8/group) that were randomly assigned to develop PAH for 1, 2, or 5 wk [right ventricle systolic pressure (RVSP) 56.5 ± 3.2, 63.6 ± 1.6, and 111.1 ± 4.5 mmHg, respectively, vs. 22.9 ± 1.1 mmHg in controls]. PAH triggered early and late episodes of apoptosis in rat lungs accompanied by RAGE activation. Mass spectrometry analysis has identified IMPA1 as a novel PAH-specific interacting partner of RAGE. The proximity ligation assay (PLA) confirmed the formation of RAGE/IMPA1 complex in the pulmonary artery wall. Activation of IMPA1 in response to increased glucose 6-phosphate (G6P) is known to play a critical role in inositol synthesis and recycling. Indeed, we confirmed a threefold increase in G6P ( P = 0.0005) levels in lungs of PAH rats starting from week 1 that correlated with accumulation of phosphatidylinositol (3,4,5)-trisphosphate (PIP3), membrane translocation of PI3K, and a threefold increase in membrane Akt levels ( P = 0.02) and Akt phosphorylation. We conclude that the formation of the newly discovered RAGE-IMPA1 complex could be responsible for the stimulation of inositol pathways and activation of Akt signaling in PAH.

Longitudinal Evaluation of Pulmonary Arterial Hypertension in a Rhesus Macaque (Macaca mulatta) Model of HIV Infection.

Pulmonary arterial hypertension (PAH) is a life-threatening disease with higher incidence in HIV-infected compared with noninfected patients. SIV-infected NHP develop clinical manifestations of HIV infection, including PAH. To understand the pathogenesis of PAH and determine the relationship between hemodynamic changes and clinical characteristics associated with SIV infection, we performed right heart catheterization and echocardiographic imaging of 21 rhesus macaques before and after SIV infection. Between 6 and 12 mo after infection, 11 of the 21 animals had elevated mean pulmonary arterial pressure (mPAP; greater than 25 mm Hg). RV involvement was evident as increased RV glucose uptake in PAH+ macaques on positron emission tomography-coupled CT compared with uninfected animals. RV and pulmonary vascular collagen deposition were elevated in PAH+ animals. At 12 mo after infection, 6 of the 21 macaques (28.6%) exhibited continued increase in mPAP (progressive PAH), whereas 5 animals (23.8%) had reduced pressure (transient PAH). SIV infection of rhesus macaques led to 3 distinct outcomes with regard to hemodynamic function. Hemodynamic alterations correlated with specific inflammatory profiles and increased RV and pulmonary arterial fibrosis but not with viral load, sex, or CD4+ T-cell levels. This model of a natural cause of PAH provides insight into disease pathways that are important for the development of novel therapeutic targets.

Abstract 16647: Loss of Reversibility in Flow-Induced Pulmonary Arterial Hypertension is Associated With a Senescent Vascular Phenotype and Can Be Rescued by Targeted Senolysis

Introduction: Patients with congenital heart disease (CHD) are at risk of developing progressive pulmonary arterial hypertension (PAH). Timely hemodynamic unloading (HU) by surgical shunt correction usually reverses the arteriopathy, but the timepoint when or reason why PAH becomes irreversible remains elusive. Methods: PAH was created in syngeneic rats by monocrotalin (MCT) injection and an aorto-caval shunt. For HU at different PAH stages, the left donor lung with PAH was transplanted into healthy recipients at t14/t21/t28. Recipients were sacrificed 21days after transplantation. Results: MCT+Shunt induced medial neomuscularization from t14, and neointimal lesions from t21, causing arteriolar occlusion and PAH. HU normalized the vascular morphology in all t14 rats and in 7/10 t21 rats, whereas no reversal or progressive occlusion occurred in 3/10 t21 and all t28 rats. RNA-sequencing revealed that activated pro-proliferative/regenerative, pro-apoptotic and DNA-repair pathways were associated with reversal after HU. This was confirmed immunohistochemically by increased vascular-specific Ki67, Caspase3 and Rad51 protein expression. In contrast, irreversibility was associated with deactivation of latter pathways and activated pro-survival, pro-senescence and pro-inflammatory pathways, as confirmed by increased Survivin, p16 ink4A , p21 cip1 , TNFα, IL6 and MMP2. These findings were also confirmed in human PAH-CHD explant tissue. Finally, we report that the senolytic BCL2 antagonist ABT263 selectively targets rat endothelial cells made senescent by irradiation. Moreover, low-dose ABT263 treatment from t25 to t32 in MCT+Shunt rats significantly improved pulmonary hemodynamics and relieved PAH symptoms. Conclusions: Similar to clinical observations in PAH-CHD, this study showed that HU reverses PAH only in an early stage, and describes a zone of no return. We characterized the mechanistic basis for (loss of) reversibility, showing a distinct switch from increased proliferation/regeneration, apoptosis and DNA-repair, to a growth arrested, apoptosis-resistant and intrinsically pro-inflammatory phenotype, suggesting a role for senescence. Reversal of this phenotype by targeted senolysis also reversed PAH beyond the zone of no return.

Prostaglandin E1 Attenuates Pulmonary Artery Remodeling by Activating Phosphorylation of CREB and the PTEN Signaling Pathway

The depletion of cyclic adenosine monophosphate (cAMP) response element binding protein (CREB) and phosphatase and tensin homolog (PTEN) is the critical mediator of pulmonary arterial hypertension (PAH). We hypothesized that the activation of phosphorylated CREB (pCREB) and PTEN could inhibit the AKT signaling pathway to attenuate pulmonary arterial remodeling in rats with monocrotaline-induced PAH. We observed decreased PTEN and pCREB in idiopathic PAH versus control tissue. We reduced PTEN using small interfering RNA in human control pulmonary arterial smooth muscle cells (PASMCs) and observed an increase in pAKT. Consistent with PTEN knockdown in PASMCs, prostaglandin E1 (PGE1) induced pCREB expression to stimulate PTEN protein expression and inhibited pAKT in a time- and dose-dependent manner. The enhanced proliferation and migration of PASMCs following PTEN knockdown were significantly inhibited by PGE1 treatment. The PGE1-induced elevation of PTEN expression in PTEN-depleted PASMCs was decreased by the application of a PKA inhibitor and a CBP-CREB interaction inhibitor. Supplementation with a novel emulsion composition comprising PGE1 in rats with monocrotaline-induced PAH prevented pulmonary arterial remodeling and improved hemodynamics via the induced expression of PTEN. We conclude that PGE1 recruits pCREB/PTEN to decrease the migration and proliferation of PASMCs associated with PAH. This finding elucidates a relevant underlying mechanism of the PGE1/CREB/PTEN signaling pathway to prevent progressive PAH.

Surgical management of aortopulmonary window: 24 years of experience and lessons learned.

Aortopulmonary window represents 0.2-0.3% of all congenital heart lesions. Progressive pulmonary arterial hypertension and its consequences are more common with this anomaly. The purpose of this study was to share 24 years of surgical experience in managing a spectrum of 55 cases of aortopulmonary window, followed up to 17 years in a single institution. This retrospective study was done from November 1991 to November 2015 of 55 patients with aortopulmonary window who underwent successful surgical repair. Age ranged from 5 months to 31 years with 45 children (12 years and younger) and 10 adults (older than 12 years). The male:female ratio was 2.2:1. The mean weight at operation was 14.63 kg (range 3.5-50 kg). An initial diagnosis was obtained from 2D echocardiography, which showed echo dropout in the parasternal short-axis view. Cardiac catheterization and angiography were performed in 54 out of 55 patients. Cardiac catheterization was not done in 1 patient who was 4 months of age. The mean right ventricular systolic pressure (RVSP) was 94 ± 2 mmHg, and the pulmonary artery mean pressure was 68 ± 2 mmHg. The average left to right shunt was 5.2:1, and the pulmonary vascular resistance index in room air was 7.97 ± 0.5 Wood units, whereas after oxygen administration, it declined to 2.0 ± 0.5 Wood units. Four surgical techniques were used based on the size of the communication and the anatomical conditions. There were no early or late deaths. There were no pulmonary hypertensive crises. All patients underwent echocardiography before discharge; none showed a residual shunt. Mild left ventricular dysfunction was seen in 2 patients. This dysfunction regressed with afterload reduction and diuretics on follow-up. All patients were followed up at intervals of 3 months, 1, 5 and 10 years, with the longest follow-up being 17 years. The mean follow-up period was 7 years. At follow-up, all patients were New York Heart Association class I. The mean RVSP on echocardiography was 32 mmHg at 3 months and 30 mmHg at 7 years with no change on further follow-up. Residual pulmonary hypertension was seen in 3 patients: 2 had mild pulmonary hypertension at 8-years follow-up and 1 had moderate hypertension at 3-months follow-up who required sildenafil postoperatively. Aortopulmonary window is a rare but well identified and surgically correctable anomaly. Operative repair should be offered as soon as the diagnosis is established, regardless of the patient's age. Irreversible pulmonary hypertension with a right to left shunt despite oxygen administration is the only contraindication for surgery. Various surgical techniques can be applied depending on the size of the communication. Associated arch anomalies may require technically challenging approaches and surgical strategies. Early and long-term outcomes after surgical correction are excellent regardless of age or pulmonary vascular resistance.

Systematic Review of Randomized Controlled Trials of Endothelin Receptor Antagonists for Pulmonary Arterial Hypertension.

There are currently three Food and Drug Administration approved endothelin receptor antagonists (ERAs): bosentan, ambrisentan, and macitentan. There is a growing body of evidence that demonstrates the beneficial effects of ERAs in patients with pulmonary arterial hypertension (PAH). To compare the available evidence from randomized clinical trials for specific outcomes of different endothelin antagonists for the treatment of PAH. A multi-database search of randomized controlled trials up to March 15, 2016 was conducted for those that would measure functional parameters of patients with PAH treated with ERA monotherapy versus placebo. Studies that analyzed 6-min walking distance, pulmonary vascular resistance, pulmonary arterial pressure, or WHO functional status were incorporated for analysis. A total of 15 trials and 2 subanalyses were compiled and quality and abovementioned outcomes were compared among studies. A constant decrease in pulmonary vascular resistance and pulmonary arterial pressure was globally reported among the different studies, resulting in increased 6-min walking distance and functional status compared to placebo. Although this evidence clearly shows the benefit of ERAs, studies, which compare ERAs against one another and with other therapies for progressive PAH, have been lacking. Larger and longer studies are necessary to define the role of ERAs as standalone agents and in combination therapies.

Parenteral Prostanoid Use at a Tertiary Referral Center: A Retrospective Cohort Study.

Evidence-based guidelines recommend the use of parenteral prostaglandin (PP) therapy in patients with advanced pulmonary arterial hypertension (PAH). Despite this, many patients with PAH die without PP therapy. We sought to examine the frequency of PP use at a large referral center and characterize patients with PAH who died without receiving PP. We conducted a single-center retrospective cohort analysis of consecutive patients with PAH between 2008 and 2012. Clinical data and cause of death were compared between patients with PAH treated with PP (PAH-PP) and those who were not but were not documented as poor PP candidates (PAH-nonPP). Of the 101 patients who received a diagnosis of PAH and died, 61 received PP therapy. Of the 40 patients not treated with PP, 10 did not have documented evaluations for PP therapy (PAH-nonPP) whereas 30 were not considered candidates or refused PP therapy. Compared with PAH-PP, PAH-nonPP had a longer 6-min walk distance, had a longer duration between time of diagnosis and date of worse functional class visit, were less likely to be diagnosed as functional class IV, and had significantly lower right atrial pressure. None of the PAH-nonPP died of progressive PAH. We found that most patients who die with PAH are evaluated for PP therapy at a large referral center and the small minority of PAH-nonPP tended to have less severe disease and die of non-PAH-related causes. Our data suggest that at large pulmonary hypertension (PH) centers, the vast majority of patients who are appropriate candidates receive PP therapy.

Constitutively active form of natriuretic peptide receptor 2 ameliorates experimental pulmonary arterial hypertension

We recently found a constitutively active mutant of natriuretic peptide receptor 2 (caNPR2; V883M), which synthesizes larger amounts of cyclic guanosine monophosphate (cGMP) intracellularly without any ligand stimulation than existing drugs. The aim of this study was to investigate the therapeutic effects of gene transduction using caNPR2 for pulmonary arterial hypertension (PAH). In vitro gene transduction into human pulmonary arterial smooth muscle cells using Sendai virus (SeV) vectors carrying caNPR2 induced 10,000-fold increases in the synthesis of cGMP without ligand stimulation, and the proliferation of caNPR2-expressing cells was significantly attenuated. The PAH model rats generated by hypoxia and the administration of SU5416 were then treated with SeV vectors through a direct injection into the left pulmonary artery. Right ventricular systolic pressure was significantly decreased 2 weeks after the treatment, while systemic blood pressure remained unchanged. Histological analyses revealed that the medial wall thickness and occlusion rate of pulmonary arterioles were significantly improved in caNPR2-treated lungs. Neither the systemic integration of virus vectors nor side effects were observed. The massive stimulation of cGMP synthesis by gene therapy with caNPR2 was safe and effective in a PAH rat model and, thus, has potential as a novel therapy for patients with severe progressive PAH.

Epidemiological Characteristics and Prospective 6-Months Follow-up of Children with Pulmonary Arterial Hypertension

Abstract Introduction: Pulmonary arterial hypertension (PAH) is a rare disease associated with significant morbidity and mortality. Pediatric patients often present with mixted aetiologies. Objectives: To characterize the epidemiology, management and outcome of pediatric PAH. Methods: Children with PAH were included and followed prospectively for six months. WHO functional class, 6-minute walk test, biomarkers, electrocardiogram, spirometers and echocardiographic parameters were evaluated in progressive PAH group. Results: Two hundred and four children were included in the study from July 2012 until July 2013, with a mean age of 6.13 years. Transient PAH patients (n=170, 83.33%) included newborns with persistent pulmonary hypertension (n=8, 3.92%) and children with congenital heart defects with systemic-to-pulmonary shuntflow PAH (n=162, 79.41%) in whom PAH resolved after successful surgery correction. Progressive PAH (n=34, 16.66%) included patients with idiopathic PAH (n=5, 2.45%), Eisenmenger syndrome (n=17, 8.33%) and post-operative PAH (n= 6, 2.94%). Patients with progressive PAH remained stable in regards to clinical status, WHO functional class, 6-minute walk distance, biomarkers, spirometers parameters and echocardiographic parameters with prognostic value. Conclusions: Pediatric PAH is characterized by various age-specific diagnoses, the majority of which comprise transient forms of PAH. Pediatric PAH associated with congenital heart defects represents a heterogeneous group with highly variable clinical courses. PAH specific therapies may have contributed to disease stability and favorable outcomes.

Severe Pulmonary Arterial Hypertensive Rats are Tolerant to Mild Exercise

A frequently used end point of clinical outcomes in patients with pulmonary arterial hypertension (PAH) is the 6-minute walk distance. Furthermore, some data suggest that mild to moderate exercise as an intervention in stable PAH is beneficial. Some of these questions have been recapitulated in the monocrotaline and hypoxia animal models of pulmonary hypertension. However, mild exercise and walk distance as end points have not been rigorously examined in the severe progressive Sugen 5416/hypoxia/normoxia (Su/Hx/Nx) animal model of PAH at each stage of worsening disease. Our hypothesis was that animals that were preselected as runners would have increased walk times and improved right ventricle/left ventricle plus septum (RV/LV+S) ratios, echocardiography, and histology compared with nonexercised Su/Hx/Nx animals. We examined four groups of rats: Su/Hx/Nx sedentary, Su/Hx/Nx exercised, control sedentary, and control exercised. Echocardiography was performed at 5, 8, and 13 weeks to assess right ventricular inner diameter in diastole and left ventricular eccentricity index. We found no difference between exercised and sedentary Su/Hx/Nx rats, and both were worsened compared with controls. Rats were euthanized at 13 weeks, and we found that neither RV/LV+S nor the occurrence of occlusive lesions were influenced by exercise. Most interesting, however, was that despite progressive PAH development, exercised Su/Hx/Nx rats showed no decrease in time or distance for treadmill exercise. In all, our data suggest that, despite severe PAH development, Su/Hx/Nx rats retain the same treadmill exercise capacity as control animals.

Exercise Does Not Attenuate Disease Progression in a Rat Model of Progressive Pulmonary Arterial Hypertension

Exercise Does Not Attenuate Disease Progression in a Rat Model of Progressive Pulmonary Arterial Hypertension