A case report of hepatopulmonary syndrome in hereditary hemorrhagic telangiectasia (HHT): Not all right-to-left shunting in HHT is due to pulmonary arteriovenous malformations

RATIONALE: Hereditary hemorrhagic telangiectasia (HHT) is an autosomal dominant disorder characterized by abnormal vessel growth that results in telangiectasias and arteriovenous malformations (AVMs) in the skin, mucosa, and viscera. Up to 30% of patients with HHT exhibit pulmonary AVMs (PAVMs), clinically manifesting as right-to-left shunting and hypoxemia. PATIENT CONCERNS: We report an unusual and novel case of a patient with HHT who lacked clinical sequelae of portal hypertension but presented to clinic with hypoxemia without dyspnea. DIAGNOSES: Diagnostic workup revealed noncardiac right-to-left shunting due to hepatopulmonary syndrome (HPS) from HHT-induced portal hypertension rather than PAVMs. The diagnosis was confirmed by the absence of PAVMs on chest computed tomography and evidence of elevated portal pressures as noted by the presence of small esophageal varices on upper endoscopy and histologic findings on liver biopsy. INTERVENTION: Due to the patient's mild symptoms, no further intervention was required. He was closely followed up in the outpatient setting for changes in symptoms and underwent annual screening for development of PAVMs. OUTCOMES: The patient continues to do well clinically. He has not experienced worsening hypoxemia or dyspnea and has not developed PAVMs. LESSONS: Given that management of hypoxemia in HPS drastically differs from that of hypoxemia due to PAVMs, this case demonstrates the importance of evaluating HHT patients for HPS if they exhibit impaired oxygenation and noncardiac right-to-leftshunting in the setting of hepatic arteriovenous shunting

Sex, Gender, and Sex Hormones in Pulmonary Hypertension and Right Ventricular Failure

Pulmonary hypertension (PH) encompasses a syndrome of diseases that are characterized by elevated pulmonary artery pressure and pulmonary vascular remodeling and that frequently lead to right ventricular (RV) failure and death. Several types of PH exhibit sexually dimorphic features in disease penetrance, presentation, and progression. Most sexually dimorphic features in PH have been described in pulmonary arterial hypertension (PAH), a devastating and progressive pulmonary vasculopathy with a 3-year survival rate <60%. While patient registries show that women are more susceptible to development of PAH, female PAH patients display better RV function and increased survival compared to their male counterparts, a phenomenon referred to as the “estrogen paradox” or “estrogen puzzle” of PAH. Recent advances in the field have demonstrated that multiple sex hormones, receptors, and metabolites play a role in the estrogen puzzle and that the effects of hormone signaling may be time and compartment specific. While the underlying physiological mechanisms are complex, unraveling the estrogen puzzle may reveal novel therapeutic strategies to treat and reverse the effects of PAH/PH. In this article, we (i) review PH classification and pathophysiology; (ii) discuss sex/gender differences observed in patients and animal models; (iii) review sex hormone synthesis and metabolism; (iv) review in detail the scientific literature of sex hormone signaling in PAH/PH, particularly estrogen-, testosterone-, progesterone-, and dehydroepiandrosterone (DHEA)-mediated effects in the pulmonary vasculature and RV; (v) discuss hormone-independent variables contributing to sexually dimorphic disease presentation; and (vi) identify knowledge gaps and pathways forward

Emerging role of angiogenesis in adaptive and maladaptive right ventricular remodeling in pulmonary hypertension

Right ventricular (RV) function is the primary prognostic factor for both morbidity and mortality in pulmonary hypertension (PH). RV hypertrophy is initially an adaptive physiological response to increased overload; however, with persistent and/or progressive afterload increase, this response frequently transitions to more pathological maladaptive remodeling. The mechanisms and disease processes underlying this transition are mostly unknown. Angiogenesis has recently emerged as a major modifier of RV adaptation in the setting of pressure overload. A novel paradigm has emerged that suggests that angiogenesis and angiogenic signaling are required for RV adaptation to afterload increases and that impaired and/or insufficient angiogenesis is a major driver of RV decompensation. Here, we summarize our current understanding of the concepts of maladaptive and adaptive RV remodeling, discuss the current literature on angiogenesis in the adapted and failing RV, and identify potential therapeutic approaches targeting angiogenesis in RV failure

Effect of Exercise on Right Ventricle Inflammation in a Rat Model of Severe Monocrotaline-Induced Pulmonary Arterial Hypertension

poster abstractPulmonary arterial hypertension (PAH) is a devastating disease of progressive remodeling of small and mid-size pulmonary arteries that leads to elevated pulmonary pressure. The work of the right heart is increased due to the elevated pulmonary pressures and can lead to maladaptive cardiac wall hypertrophy, right heart failure and then eventually death. Whether exercise-induced cardiac stress also promotes detrimental right ventricle (RV) inflammation in PAH has not been thoroughly examined. The purpose of this study is to determine if treadmill exercise at low relative intensity in a rat model of severe PAH without promoting greater RV inflammation. Adult male Sprague- Dawley rats were injected with monocrotaline (60mg/kg, subcutaneously, n=14) or saline (healthy controls, n=4). RV tissue was obtained from these rats following a 6 week, 5 times/week treadmill training program at a low intensity of 50% of measured aerobic capacity (VO2max) and compared to tissue obtained from sedentary counterparts. RV immunofluorescent staining for CD45, a lymphocyte marker, was performed to evaluate the inflammatory response due to chronic exercise training. The experiment is still underway and the expected result is that there is no greater exercised induced RV inflammation in PAH rats compared to healthy rats

Hypoxia Upregulates Estrogen Receptor β in Pulmonary Artery Endothelial Cells in a HIF-1α-Dependent Manner

17β-Estradiol (E2) attenuates hypoxia-induced pulmonary hypertension (HPH) through estrogen receptor (ER)-dependent effects, including inhibition of hypoxia-induced endothelial cell proliferation; however, the mechanisms responsible for this remain unknown. We hypothesized that the protective effects of E2 in HPH are mediated through hypoxia-inducible factor 1α (HIF-1α)-dependent increases in ERβ expression. Sprague-Dawley rats and ERα or ERβ knockout mice were exposed to hypobaric hypoxia for 2-3 weeks. The effects of hypoxia were also studied in primary rat or human pulmonary artery endothelial cells (PAECs). Hypoxia increased expression of ERβ, but not ERα, in lungs from HPH rats as well as in rat and human PAECs. ERβ mRNA time dependently increased in PAECs exposed to hypoxia. Normoxic HIF-1α/HIF-2α stabilization increased PAEC ERβ, whereas HIF-1α knockdown decreased ERβ abundance in hypoxic PAECs. In turn, ERβ knockdown in hypoxic PAECs increased HIF-2α expression, suggesting a hypoxia-sensitive feedback mechanism. ERβ knockdown in hypoxic PAECs also decreased expression of the HIF inhibitor prolyl hydroxylase 2 (PHD2), whereas ERβ activation increased PHD2 and decreased both HIF-1α and HIF-2α, suggesting that ERβ regulates the PHD2/HIF-1α/HIF-2α axis during hypoxia. Whereas hypoxic wild-type or ERα knockout mice treated with E2 demonstrated less pulmonary vascular remodeling and decreased HIF-1α after hypoxia compared with untreated hypoxic mice, ERβ knockout mice exhibited increased HIF-2α and an attenuated response to E2 during hypoxia. Taken together, our results demonstrate a novel and potentially therapeutically targetable mechanism whereby hypoxia, via HIF-1α, increases ERβ expression and the E2-ERβ axis targets PHD2, HIF-1α, and HIF-2α to attenuate HPH development

Distinct immunologic and radiographic patterns in etanercept-induced lung injury

Nonspecific clinical presentation of non-infectious, immune-mediated pulmonary complications of etanercept therapy makes the diagnosis difficult. While bronchoalveolar lavage fluid (BALF) cell analysis is frequently used in diagnosing drug-induced lung disease, BALF patterns in etanercept-induced lung injury (EILI) are not well established. Furthermore, previous reports of EILI diagnosis relied on transbronchial or surgical lung biopsies. Here, we report two patients who developed pulmonary toxicity after etanercept treatment. Both patients were diagnosed with EILI. While one patient presented with CD4(+)-predominant lymphocytic alveolitis (consistent with a sarcoid-like pattern), the other patient exhibited a CD8(+)-predominant pattern (consistent with hypersensitivity pneumonitis-like reaction). The different BAL patterns were accompanied by distinct radiographic findings. Both patients significantly improved after etanercept discontinuation and corticosteroid initiation. We propose that EILI can present with distinct immunologic and radiographic phenotypes. In addition, early BALF analysis with lymphocyte immunophenotyping can further define the underlying immunologic abnormalities, and thereby, avoid more invasive procedures

Cardiac and Skeletal Muscle Lipotoxicity in a Rat Model of Pulmonary Arterial Hypertension

poster abstractPatients with Pulmonary Arterial Hypertension (PAH)experience shift from aerobic to anaerobic respiration in cardiac and skeletal muscle myocytes. This shift can be identified histologically by an increased presence of the glucose transporter Glut 1 in the tissue, indicating increased reliance on cytoplasmic glycolysis. Previous studies have demonstrated that in patients with diabetes, an increase in Glut 1 is accompanied by an increase in fat storage in the cell. Excessive myocyte fat storage may contribute to tissue and systemic inflammation and has therefore been termed ‘lipotoxicity’. This study tested the hypothesis in a PAH rat model that an increase in cardiac and skeletal muscle Glut 1 abundance would be associated with an increase in fat storage in the cell. Oil Red O staining was performed to assay for lipotoxicity in cryosections of right ventricle and soleus muscle tissue, imaged using brightfield microscopy. The experiment was conducted using tissue from a moderately severe PAH phenotype produced by monocrotaline(60 mg/kg) injection, as well as from saline injected control animals. Lipids have been observed in the first few samples tested with Oil Red O staining, and results are still pending as a larger sample size is currently being collected

Derivation of a screening tool to identify patients with right ventricular dysfunction or tricuspid regurgitation after negative computerized tomographic pulmonary angiography of the chest

Many dyspneic patients who undergo computerized tomographic pulmonary angiography (CTPA) for presumed acute pulmonary embolism (PE) have no identified cause for their dyspnea yet have persistent symptoms, leading to more CTPA scanning. Right ventricular (RV) dysfunction or overload can signal treatable causes of dyspnea. We report the rate of isolated RV dysfunction or overload after negative CTPA and derive a clinical decision rule (CDR). We performed secondary analysis of a multicenter study of diagnostic accuracy for PE. Inclusion required persistent dyspnea and no PE. Echocardiography was ordered at clinician discretion. A characterization of isolated RV dysfunction or overload required normal left ventricular function and RV hypokinesis, or estimated RV systolic pressure of at least 40 mmHg. The CDR was derived from bivariate analysis of 97 candidate variables, followed by multivariate logistic regression. Of 647 patients, 431 had no PE and persistent dyspnea, and 184 (43%) of these 431 had echocardiography ordered. Of these, 64 patients (35% [95% confidence interval (CI): 28%-42%]) had isolated RV dysfunction or overload, and these patients were significantly more likely to have a repeat CTPA within 90 days (P = .02, [Formula: see text] test). From univariate analysis, 4 variables predicted isolated RV dysfunction: complete right bundle branch block, normal CTPA scan, active malignancy, and CTPA with infiltrate, the last negatively. Logistic regression found only normal CTPA scanning significant. The final rule (persistent dyspnea + normal CTPA scan) had a positive predictive value of 53% (95% CI: 37%-69%). We conclude that a simple CDR consisting of persistent dyspnea plus a normal CTPA scan predicts a high probability of isolated RV dysfunction or overload on echocardiography