Changes In Pulmonary Hypertension Research Articles

Continuous heart monitoring to evaluate treatment effects in pulmonary hypertension

BackgroundThe treatment of pulmonary hypertension (PH) has improved rapidly in recent decades. There is increasing evidence to support the role of early intervention and treatment in affecting clinical outcomes in...

Prognostic Implication of Pulmonary Hypertension in Low-Flow Low-Gradient Aortic Stenosis After Transcatheter Aortic Valve Replacement

Prognostic implications of pulmonary hypertension (PH) in low-flow low-gradient (LG) aortic stenosis (AS) after transcatheter aortic valve replacement (TAVR) remains unexplored. We aimed to investigate the impact of baseline and changes in PH after TAVR. In this single-center retrospective study, we included patients who underwent TAVR for low-flow LG AS. Patients were categorized into 2 groups: baseline pulmonary artery systolic pressure (PASP) <46mm Hg (no-to-mild PH) and PASP ≥46mm Hg (moderate-to-severe PH). On the basis of changes in PASP after TAVR, patients were stratified into increased (ΔPASP ≥+5 mm Hg), no change (-4 to +4 mm Hg), and decreased (≤ -5 mm Hg) groups. Primary end point was a composite of all-cause mortality and heart failure rehospitalization. In total, 210 patients were included, 148 in the no-to-mild PH group and 62 in the moderate-to-severe PH group. Median follow-up was 13.2 months. The moderate-to-severe PH group was at an increased risk of composite end point (adjusted hazard ratio [HR] 3.5, 95% confidence interval [CI] 1.8 to 6.9), all-cause mortality (HR 2.4, 95% CI 1.1 to 5.6), and heart failure rehospitalization (HR 8.3, 95% CI 2.9 to 23.7). There were no differences in clinical outcomes among those with increased (32%), no change (28%), and decreased (39%) PASP after TAVR. In conclusion, moderate-to-severe PH at baseline is an independent predictor of worse clinical outcomes in patients with low-flow LG AS who undergo TAVR, and this cohort of patients do not seem to derive the benefits of postoperative reduction of PASP.

Cysteine and glycine rich protein 2 exacerbates vascular fibrosis in pulmonary hypertension through the nuclear translocation of yes-associated protein and transcriptional coactivator with PDZ-binding motif

Pulmonary hypertension (PH) is a serious cardiovascular disease with a poor prognosis and high mortality. The pathogenesis of PH is complex, and the main pathological changes in PH are abnormal hypertrophy and vessel stiffness. Cysteine and glycine rich protein 2 (Csrp2), a member of the LIM-only family plays a key role in the response to vascular injury. However, its roles in vascular fibrosis and PH have not been clarified. Therefore, this study aimed to investigate whether Csrp2 can promote vascular fibrosis and to further explore the possible mechanisms. Csrp2 expression was increased in both the pulmonary vasculature of rats with PH and hypoxic pulmonary vascular smooth muscle cells (PASMCs). Hypoxia activated TGF-β1 and its downstream effector, SP1. Additionally, hypoxia activated the ROCK pathway and inhibited KLF4 expression. Silencing SP1 and overexpressing KLF4 reversed the hypoxia-induced increase in Csrp2 expression. Csrp2 knockdown decreased the expression of extracellular matrix (ECM) proteins and inhibited the nuclear translocation and expression of YAP/TAZ in hypoxic PASMCs. These results indicate that hypoxia induces Csrp2 expression through the TGF-β1/SP1 and ROCK/KLF4 pathways. Elevated Csrp2 promoted the nuclear translocation and expression of YAP/TAZ, leading to vascular fibrosis and the development of PH.

Abstract 15671: Targeting Chromatin Structure: The Combined Inhibition of Histone Deacetylases and Bromodomain Proteins in Normalizing Persistently Activated Pulmonary Hypertensive Fibroblasts

Rationale: The multifactorial nature of pulmonary hypertension (PH) suggests epigenetic changes as potential determinants of vascular remodeling through regulating gene expression (both up-regulated and down-regulated genes) in vascular cells. Changes in the chromatin state (especially histone acetylation) of specific genes can lead to their repression or activation. We and others have demonstrated histone deacetylases inhibitors (HDACi) and histone acetylation readers inhibitors (BRDi) can prevent and ameliorate PH changes by normalizing pathological gene expression. However, the non-histone protein targets and the narrow therapeutic window of currently available HDACi limits their clinical utility. In this study, we evaluated the effect of combination treatments using a new HDACi (OKI-005, US patent) with high potency and selectivity for HDACs (targeting decreased genes) together with BRDi (targeting increased genes), in low doses. Methods and Results: Cultured human pulmonary artery fibroblasts derived from patients with IPAH (PH-Fibs) or from control donors (CO-Fibs) were used as in vitro model system. PH-Fibs exhibit increased pro-inflammatory genes (e.g. CXCL12), proliferation markers (e.g. Mki67) and anti-apoptosis genes (e.g. BCL2) as well as decreased anti-inflammatory genes (e.g. HMOX1), anti-proliferation genes (e.g. P21) and pro-apoptotic genes (e.g. PERP). In PH-Fibs, the increased expressed CXCL2 gene exhibited more opened chromatin structure and BRD4 binding (ChIP-assay), and BRDi (JQ1) can decrease its expression in a dose dependent trend. At the low doses, JQ1 (100 nM) alone is sufficient to normalize most of increased genes, while the new HDACi (OKI-005) was more effective in normalizing decreased genes in PH- Fibs. The combination of low dose of JQ1 (100 nM) and OKI-005 (64 nM) was sufficient to normalize both increased genes and decreased genes thus inhibiting the persistently activated PH-phenotype without deleterious effects on CO-Fibs. Conclusion: Combination of HDACi and BRDi in low doses is effective in normalizing the persistent activation of PH-Fibs without deleterious effects on control cells, offering promise for epigenetic-targeted therapies in PH.

Early histological changes of bronchopulmonary dysplasia and pulmonary hypertension may precede clinical diagnosis in preterm infants

Bronchopulmonary Dysplasia (BPD), the commonest complication of prematurity, is defined by treatment with oxygen for ≥28 days. Pulmonary hypertension (PH) often coexists with BPD and is associated with increased mortality. In 42 autopsies, histological changes of BPD and PH were demonstrated in 25 % and 65 % respectively of preterm infants <28 days of age, highlighting the need for early diagnosis and treatment.

Brief Report: Case Comparison of Therapy With the Histone Deacetylase Inhibitor Vorinostat in a Neonatal Calf Model of Pulmonary Hypertension.

Pulmonary hypertension (PH) is an incurable condition in humans; driven by pulmonary vascular remodeling partially mediated by epigenetic mechanisms; and leading to right ventricular hypertrophy, failure, and death. We hypothesized that targeting chromatin-modifying histone deacetylases may provide benefit. In this Brief Report we describe case comparison studies using the histone deacetylase inhibitor vorinostat (suberanilohydroxamic acid, 5 mg/kg/day for the first 5 study days) in an established model of severe neonatal bovine PH induced by 14 days of environmental hypoxia. Echocardiographic, hemodynamic, and pharmacokinetic data were obtained in hypoxia-exposed (one each, vorinostat-treated vs. untreated) and normoxic vorinostat-treated control animals (n = 2). Echocardiography detected PH changes by day 4 and severe PH over 14 days of continued hypoxic exposure. RV dysfunction at day 4 was less severe in vorinostat-treated compared to untreated hypoxic calves. Cardioprotective effects were partially maintained following cessation of treatment through the duration of hypoxic exposure, accompanied by hemodynamic evidence suggestive of reduced pulmonary vascular stiffening, and modulated expression of HDAC1 protein and genes involved in RV and pulmonary vascular remodeling and pathological RV hypertrophy. Control calves did not develop PH, nor show adverse cardiac or clinical effects. These results provide novel translation of epigenetic-directed therapy to a large animal severe PH model that recapitulates important features of human disease.

THE EFFECT OF LEFT VENTRICULAR ASSIST DEVICES (LVAD) ON PULMONARY HYPERTENSION IN END-STAGE HEART FAILURE: A MULTICENTER STUDY.

The prevalence of heart failure in North America is predicted to increase by nearly 50% over 15 years. Once pharmacological options have been exhausted, therapeutic interventions in end-stage heart failure are limited to heart transplantation and mechanical support such as left-ventricular assist devices (LVAD). Despite an increasing prevalence of advanced heart failure, transplantation rates have remained stable in Canada due to limited organ availability. As a consequence of this, the number of implanted LVADs and average time on device support have both risen rapidly. End-stage heart failure is often complicated by pulmonary hypertension (PHTN) which results in worsened symptomatology, decreased exercise capacity, and increased mortality. Patients with PHTN have historically not been considered candidates for transplantation but recent reports of PHTN reversibility with LVAD support have led to changes to the ISHLT listing criteria which now state that pulmonary hemodynamics should be reassessed 3 to 6 months following LVAD implantation for PHTN reversibility and potential transplantation candidacy. All patients having received a permanent LVAD at the Maritime Heart Center (Halifax, NS) and Brigham and Women's Hospital (Boston, MA) were included in our study. Pre-operative characteristics were obtained from institutional databases. Right-heart catheterization data was retrospectively retrieved for 90 days pre-insertion and up to 3 years post-insertion. Pulmonary vascular resistance (PVR) was calculated for each instance from the transpulmonary gradient and measured cardiac output. A generalized estimating equation was used to determine if any pre-operative variable was associated with PHTN reversibility. 214 patients for a total of 655 pulmonary hemodynamic measurements were captured and their peri-operative characteristics are summarized in Table 1. Patients with pre-operative PHTN (defined as a pre-operative PVR > 3 Wood Units) were less likely to have an ischemic etiology but were otherwise similar to the normotensive cohort. Longitudinal PVR measurements for patients with and without pre-operative PHTN are visualized in Figure 1 and most patients had normalization of their pulmonary hemodynamics 6 months post-operatively. Our regression model revealed that pre-operative PVR was the only variable significantly associated with subsequent changes in PHTN. In our study population, LVAD use led to reversibility of PHTN for the majority of patients within the 6-month window suggested by the ISHLT. With the exception of pre-operative PVR, no other peri-operative variable was significantly associated with reversibility of PHTN.View Large Image Figure ViewerDownload Hi-res image Download (PPT)

Sarcoidosis Associated Pulmonary Hypertension: Correlation of Cascular Morphologic Changes with Hemodynamic Data in Explanted Lungs

Purpose Sarcoidosis associated pulmonary hypertension (PH) is classified as WHO Group V according to the 2018 WHO classification system. Previous case series have demonstrated efficacy of pulmonary vasodilators in treating severe PH in sarcoidosis. We present a series of patients with sarcoidosis associated PH and describe correlation between the pre-transplant hemodynamic data from a right heart catheterization (RHC) and vascular morphologic changes in the native explanted lungs. Methods Patients with sarcoidosis who underwent lung transplantation at Loyola University Medical Center were analyzed from 2014-2018. We collected demographic data, RHC data, NYHA functional class data, and echocardiogram. Pathology was reviewed to assess for presence and severity of fibrosis, presence or absence of granulomas in lung parenchyma and lymph nodes, and vascular morphologic changes using Heath Edwards PH classification. We evaluated PH changes in arterioles, muscular arteries of 1mm and 3mm caliber, and elastic arteries. These findings were correlated to RHC data. Results Seven patients who had a RHC prior to lung transplantation were identified and had a mean pulmonary artery pressure greater than 25 mmHg. All of the patients had well-formed granulomas except two cases that showed ill formed granulomas. 5 of 7 cases had lymph nodes involved and 5 of 7 had fibrosis. Medial hypertrophy of 1 and 3mm arteries was observed in all cases. 3 of 4 patients with severe PH (NYHA Class IV) and RV dysfunction on echocardiogram were on parenteral prostacyclin therapy at the time of transplant and had grade 3 changes in the 1 mm arteries and grade 2 changes in the 3 mm arteries. Only 2 of 7 cases showed arteriolar changes, which correlated with higher pressures. No plexiform lesions were seen in any of the patients. Conclusion In our series of sarcoidosis patients with PH who underwent lung transplant or transplantation, vascular morphologic changes at the level of the 1 mm and arterioles correlated with the presence of severe PH (NYHA Class IV) and RV dysfunction on echocardiogram. These patients lack the plexiform lesions typically seen in idiopathic pulmonary arterial hypertension. Our study may identify a subset of sarcoid patients who have significant vascular remodeling and possibly explains the recently observed favorable response to vasodilator therapy.

Влияние степени гипоксии, пола животного и 17β-эстрадиола на проявления гипоксической формы легочной гипертензии

We studied the effect of chronic administration of female sex hormone –17β estradiol (E2) at a dose of 15 µg/kg/day on the development of pulmonary hypertension (PH) caused by intermittent hypoxia with O2 content of 13%, 10%, and 8% for 2 weeks. The study was carried out on gonadoectomized Wistar rats of both sexes. The degree of PH development was assessed by the magnitude of right ventricular systolic pressure (RVSP) and right ventricular hypertrophy. It was shown that all animals exposed to hypoxia developed PH, the degree of which depended on the O2 concentration in the inhaled air. In males, the hypoxia (10% O2) increased the RVSP 19% less than in females (p <0.05). Chronic administration of E2 caused gender-dependent changes in PH only at 10% O2. Thus, in males, the administration of E2 increased RVSP by 31% (p <0.05), and in females it reduced hypertrophy by 10%. Also, E2 increased the survival rate of females at 8% O2 by 2.5 times, but not males. An increase in hematocrit during hypoxia (10% O2) in females occurred due to an increase in the number of erythrocytes, and in males - due to an increase in their volume. Thus, the degree of development of the hypoxic pulmonary hypertension depends on the O2 concentration in the inhaled air and has gender differences. E2 affects the development of this disease.

Principles of pharmacological correction of pulmonary arterial hypertension

Definition and classification: Pulmonary hypertension (PH) is a group of life-threatening progressive diseases of various genesis, characterized by a progressive increase in arterial pressure (AP) in the pulmonary artery (PA), the remodeling of pulmonary vessels, which leads to an increase in pulmonary vascular resistance and pulmonary arterial pressure and more often leads to right ventricular heart failure and premature death. Pulmonary hypertension is clinically divided into five groups: patients in the first group have idiopathic pulmonary arterial hypertension (IPAH), whereas in patients of other groups secondary PH associated with cardiopulmonary or other systemic diseases is observed. The development of secondary LH is caused by congenital heart defects, collagenoses, presence of thrombus in the pulmonary artery, prolonged high pressure in the left atrium, hypoxemia, chronic obstructive pulmonary diseases (COPDs). In case of secondary PH, thrombosis and other changes in the pulmonary veins occur.&#x0D; Ways of pharmacological correction of pulmonary hypertension: Over the last decade pharmacotherapy of PH has been developing rapidly, and the introduction of modern methods of treatment, especially for primary PAH, has led to positive results. However, despite the progress in treatment, the functional limitations and survival of patients remain unsatisfactory. Currently, there are two levels of treatment for pulmonary hypertension: primary and specific pathogenetic therapies. Primary therapy is aimed at the main cause of PH. It also includes supportive therapy. Pathogenetic therapy includes prostanoids, endothelin receptor antagonists, and phosphodiesterase-5 inhibitors. Tactics of therapy can be established on the basis of either clinical classification, or functional class. Prostanoids are a promising group of drugs for the treatment of pulmonary arterial hypertension (PAH), since they possess not only vasodilating, but also antiplatelet and antiproliferative actions. Therefore, it seems logical to use prostacyclin and its analogs to treat patients with various forms of PAH.

Abstract 235: Plasma Levels of Cyclophilin A Correlate with Circulating Inflammatory Cytokines in Patients with Pulmonary Hypertension

Background: Excessive proliferation and resistance to apoptosis of pulmonary artery smooth muscle cells (PASMCs) are key characteristics of pulmonary vascular remodeling in patients with pulmonary hypertension (PH). The mechanisms of pathophysiological changes in PH are not fully investigated. Cyclophilin A (CyPA) is secreted from vascular smooth muscle cells (VSMCs) in response to several stimuli, including oxidative stress, mechanical stretch and hypoxia. Extracellular CyPA and its receptor Basigin induce secretion of growth factors and inflammatory cytokines from VSMCs. Additionally, plasma CyPA levels predict poor outcome in patients with PH. In this study, we examined the correlations between plasma CyPA levels and circulating cytokines/chemokines and growth factors in PH patients. Methods and Results: In consecutive 176 patients undergoing right heart catheterization, we examined the relationship between plasma CyPA and inflammatory cytokines/chemokines and growth factors. We used ELISA for CyPA measurement and Bio-Plex system for measurement of inflammatory cytokines/chemokines and growth factors. Plasma CyPA levels in PH patients increased according to their severity assessed by pulmonary vascular resistance (P&lt;0.001). A positive correlation was noted between plasma CyPA levels and several inflammatory cytokines/chemokines and growth factors, including CXCL1 (P&lt;0.001), CXCL9 (P=0.001), macrophage colony-stimulating factor (P=0.020), SDF-1α (P=0.005) and PDGF-BB (P=0.003). Interestingly, there was a significant correlation between plasma levels of CyPA and those of LDL-cholesterol (P=0.003) or HbA1c (P=0.006). In contrast, there was no correlation between CyPA and high-sensitivity CRP (P=0.172). Finally, plasma levels of CyPA and SDF-1α were significantly less in patients with statins (both P&lt;0.01). Conclusions: Plasma levels of CyPA are correlated with those of circulating cytokines/chemokines and growth factors, suggesting an inflammatory role of CyPA in PH patients. These data further support the crucial role of CyPA as a pathogenic molecule and a therapeutic target in PH.

Sarpogrelate hydrochloride, a serotonin 5HT2A receptor antagonist, ameliorates the development of chronic hypoxic pulmonary hypertension in rats.

The purpose of the present study was to determine if sarpogrelate hydrochloride (SPG), a serotonin 5HT2A receptor antagonist, prevented the development of chronic hypoxia-induced pulmonary hypertension (PH) and hypertensive pulmonary vascular remodeling. Forty-one male Sprague-Dawley rats were exposed to hypobaric hypoxia (380 mmHg, 10 % oxygen) or room air and administered 50 mg/kg SPG or vehicle by gavage once daily from day -2 to day 14. The mean pulmonary artery pressure (PAP) and right ventricular hypertrophy (RVH) were measured. Hypertensive pulmonary vascular remodelings were assessed morphometrically by light microscopy. Serotonin-induced contraction was determined in isolated pulmonary artery rings from 24 rats. In another set of rats, Western blotting, real-time polymerase chain reaction and immunofluorescent staining (n = 9) for lung tissue were performed. Chronic hypoxia induced a rise in mean PAP and RVH, increased the percentage of muscularized arteries in peripheral pulmonary arteries and medial wall thickness in small muscular arteries, and potentiated serotonin-induced contraction, each of which was significantly (p < 0.05) ameliorated by SPG. Chronic hypoxia significantly increased the expression of endothelial nitric oxide synthase (eNOS) and phosphorylated eNOS (peNOS) protein levels, cyclic guanosine monophosphate, and matrix metalloproteinase-13 (MMP-13) mRNA levels in whole lung tissues. SPG increased peNOS expression in the immunofluorescent staining of peripheral pulmonary arteries from chronic hypoxic rats and decreased the MMP-13 mRNA in lung tissue in chronic hypoxic rats. The administration of SPG ameliorated the development of chronic hypoxic PH and hypertensive pulmonary vascular changes.

Pathophysiology and potential treatments of pulmonary hypertension due to systolic left heart failure

Pulmonary hypertension (PH) due to left heart failure is becoming increasingly prevalent and is associated with poor outcome. The precise pathophysiological mechanisms behind PH due to left heart failure are, however, still unclear. In its early course, PH is caused by increased left ventricular filling pressures, without pulmonary vessel abnormalities. Conventional treatment for heart failure may partly reverse such passive PH by optimizing left ventricular function. However, if increased pulmonary pressures persist, endothelial damage, excessive vasoconstriction and structural changes in the pulmonary vasculature may occur. There is, at present, no recommended medical treatment for this active component of PH due to left heart failure. However, as the vascular changes in PH due to left heart failure may be similar to those in pulmonary arterial hypertension (PAH), a selected group of these patients may benefit from PAH treatment targeting the endothelin, nitric oxide or prostacyclin pathways. Such potent pulmonary vasodilators could, however, be detrimental in patients with left heart failure without pulmonary vascular pathology, as selective pulmonary vasodilatation may lead to further congestion in the pulmonary circuit, resulting in pulmonary oedema. The use of PAH therapies is therefore currently not recommended and would require the selection of suitable patients based on the underlying causes of the disease and careful monitoring of their progress. The present review focuses on the following: (i) the pathophysiology behind PH resulting from systolic left heart failure, and (ii) the current evidence for medical treatment of this condition, especially the role of PAH-targeted therapies in systolic left heart failure.

Three‐Dimensional Analysis of Right Ventricular Shape and Function in Pulmonary Hypertension

Right ventricular (RV) failure is a key determinant of morbidity and mortality in pulmonary hypertension (PH). The present study aims to add to existing descriptions of RV structural and functional changes in PH through a comprehensive three-dimensional (3D) shape analysis. We performed 3D echocardiography on 53 subjects with PH and 19 normal subjects. Twenty short-axis slices from apex to tricuspid centroid were measured to characterize regional shape: apical angle, basal bulge, eccentricity, and area. Transverse shortening was assessed by fractional area change (FAC) in each short-axis slice, longitudinal contraction was assessed by tricuspid annular plane systolic excursion (TAPSE) and global function by RV ejection fraction. Multivariate logistic analysis was used to compare the association of RV parameters with New York Heart Association (NYHA) class. Compared to normal, RV function in PH is characterized by decreased stroke volume index (SVi), fractional area change and ejection fraction. Increased eccentricity, apical rounding and bulging at the base characterize the shape of the RV in PH. Increased SVi, ejection fraction and mid-ventricular FAC were associated with less severe NYHA class in adjusted analyses. The RV in idiopathic PH (iPAH) was observed to have a larger end-diastolic volume and decreased function compared with connective tissue disease associated PH (ctd-PH). This work describes increased eccentricity and decreased systolic function in subjects with PH. Functional parameters were associated with NYHA class and heterogeneity in the phenotype was noted between subjects with iPAH and ctd-PH.

Nitric oxide-independent stimulation of soluble guanylate cyclase attenuates pulmonary fibrosis

Background Pulmonary fibrosis (PF) is a ni ncreasing cause of morbidity and mortality with five million people affected worldwide and a median survival time of less than three years. Effective anti-fibrotic agents for PF are currently lacking. The majority of patients with PF develop pulmonary hypertension (PH) and right heart failure. Impaired production of endogenous nitric oxide (NO) plays an important role in the pathogenesis of PF-associated PH. The NO signaling pathway involves activation of soluble guanylate cyclase (sGC) with subsequent generation of cGMP. We hypothesized that sGC might be involved in the pathogenesis of PF and that the NOindependent stimulation of sGC might attenuate PH and fibrotic changes in a clinically relevant mouse model of PF. Materials and methods

Pulmonary hypertension secondary to interstitial lung disease

Interstitial lung diseases (ILDs) may be complicated by the development of pulmonary hypertension (PH), which is associated with worse functional impairment and a poorer prognosis. This article reviews the current state of knowledge on the prevalence, pathogenesis, diagnosis and prognosis of ILD-related PH. Whether the treatment of ILD-related PH changes clinical outcomes is currently unknown, but the current studies are summarized and the authors’ perspective is offered.

Pulmonary Artery Thrombosis in Experimental Angiostrongylus vasorum Infection Does Not Result in Pulmonary Hypertension and Echocardiographic Right Ventricular Changes

Dogs experimentally inoculated with Angiostrongylus vasorum develop severe pulmonary parenchymal lesions and arterial thrombosis at the time of patency. A. vasorum-induced thrombosis results in arterial hypoxemia, pulmonary hypertension (PH), and altered cardiac morphology and function. Six healthy Beagles experimentally inoculated with A. vasorum. Thoracic radiographs and arterial blood gas analyses were performed 8 and 13 weeks postinoculation (wpi) and 9 weeks posttherapy (wpt). Echocardiography was done before and 2, 5, 8, 13 wpi and 9 wpt. Invasive pulmonary artery pressure (PAP) measurements were obtained 8 wpi. Two untreated dogs were necropsied 13 wpi and 4 treated dogs 9 wpt. All dogs had patent infections at 7 wpi and clinical respiratory signs at 8 wpi. Moderate hypoxemia (median PaO2 of 73 and 74 mmHg) present at 8 and 13 wpi had resolved by 9 wpt. Echocardiographically, no evidence of PH and no abnormalities in cardiac size and function were discernible at any time point. PAP invasively measured at 8 wpi was not different from that of control dogs. Severe radiographic pulmonary parenchymal and suspected thrombotic lesions at 13 wpi were corroborated by necropsy. Most histopathologic changes had resolved at 9 wpt, but focal inflammatory, thrombotic, and fibrotic changes still were present in all dogs. In experimentally infected Beagles, pulmonary and vascular changes induced by A. vasorum are reflected by marked radiographic changes and arterial hypoxemia. These did not result in PH and echocardiographic changes in cardiac size and function.

Nitric oxide synthase 3 and endothelin 1 immunoreactivity in pulmonary hypertension

Pulmonary hypertension (PH) is a serious and sometimes life-threatening event that occurs as a complication of various cardiopulmonary disorders, of which rheumatic heart disease (RHD) is an important example in our country. The pathogenesis of PH is a complex, multistep process in which "pulmonary endothelial dysfunction" (PED) is widely regarded as the central pathogenetic event. PED is, in turn, influenced by several local and systemic factors, of which nitric oxide synthase 3 (NOS3) and endothelin 1 (ET1) are 2 prime candidates, and are the subject of our study. Our aim was to study the immunoreactivity of NOS3 and ET1 in the pulmonary vasculature of PH patients of various etiologies, with emphasis on RHD cases. A retrospective, autopsy-based study. A total of 49 autopsy cases (39 patients and 10 controls) were chosen for our study. Of the 39 patients, 20 had PH secondary to RHD, whereas the remaining 19 patients had non-RHD etiologies as the basis of their PH. Lung sections taken from all the 49 cases were subjected to routine H and E, elastic van Gieson, and immunohistochemical staining (with NOS3 and ET1 separately). The intensity of immunostaining in all the cases and controls were then graded as focal/diffuse and weak/strong. Controls showed positivity for both NOS3 (bronchiolar epithelium) and ET1 (endothelium of pulmonary arteries). Characteristic changes of PH on H and E were seen in 14 out of 19 non-RHD cases, which matched with the number of ET1 positivity cases. Similarly, for the RHD cases, 14 out of 20 cases showed changes of PH on H and E, but only 2 cases showed mild, focal positivity for ET1. Surprisingly, NOS3 positivity was largely absent in both the non-RHD and RHD cases. Our study showed NOS3 negativity and ET1 positivity in the lung vasculature of patients with PH, a conclusion more or less in line with the predominant view of the other investigators in this field. But at the same time, our study could not conclude an unequivocal role of NOS3 in PH, whereas it could, in the case of ET1.

PULMONARY HYPERTENSION AND VALVULAR HEART DISEASE: INCIDENCE AND IMMEDIATE IMPACT OF SURGICAL REPAIR

PURPOSE: Mitral and aortic valve diseases can cause secondary pulmonary hypertension (PH). Initially, PH is due to increased left atrial pressure but with time pulmonary vascular remodeling can occur. The former should rapidly improve with surgery; the latter would be more likely persist. We initiated this study to assess the frequency of and changes in PH in patients with aortic (AVR) versus mitral valve (MVR)repair both immediately before and 24 hours after surgery.

In Utero Development of Hypertensive Necrotizing Pulmonary Arterial Lesions: Report of a Case Associated with Premature Closure of the Ductus Arteriosus and Pulmonary Hypoplasia

Premature closure of the ductus arteriosus (PCDA) is an uncommon defect in which pulmonary hypertension (PH) has been documented by echocardiography in patients and by direct measurement after experimental PCDA in animals. The pulmonary vascular histology in human cases has received little attention but in the few recorded observations the vessels were either normal or showed increased muscularity. We report the case of a 31 week hydropic female stillborn monozygotic twin in whom postmortem examination disclosed PCDA and hypoplasia of the lungs. Atypical plexiform lesions with necrotizing pulmonary arteritis were present. These lesions represent vascular consequences of severe pulmonary hypertension produced by greatly enhanced blood flow through a restricted vascular bed resulting from the combined effects of these two abnormalities. The findings in this case of PCDA with presumed severe PH indicate that severe pulmonary vascular changes can develop in utero and that the interval of time needed for development of such changes in secondary PH is relatively short.