Pulmonary Vascular Function Research Articles

Junctional complex and focal adhesion rearrangement mediates pulmonary endothelial barrier enhancement by FTY720 S-phosphonate

RationaleModulation of pulmonary vascular barrier function is an important clinical goal given the devastating effects of vascular leak in acute lung injury (ALI). We previously demonstrated that FTY720 S-phosphonate (Tys), an analog of sphingosine 1-phosphate (S1P) and FTY720, has more potent pulmonary barrier protective effects than these agents in vitro and in mouse models of ALI. Tys preserves expression of the barrier-promoting S1P1 receptor (S1PR1), whereas S1P and FTY720 induce its ubiquitination and degradation. Here we further characterize the novel barrier promoting effects of Tys in cultured human pulmonary endothelial cells (EC). Methods/ResultsIn human lung EC, Tys significantly increased peripheral redistribution of adherens junction proteins VE-cadherin and β-catenin and tight junction protein ZO-1. Inhibition of VE-cadherin with blocking antibody significantly attenuated Tys-induced transendothelial resistance (TER) elevation, while ZO-1 siRNA partially inhibited this elevation. Tys significantly increased focal adhesion formation and phosphorylation of focal adhesion kinase (FAK). Pharmacologic inhibition of FAK significantly attenuated Tys-induced TER elevation. Tys significantly increased phosphorylation and peripheral redistribution of the actin-binding protein, cortactin, while cortactin siRNA partially attenuated Tys-induced TER elevation. Although Tys significantly increased phosphorylation of Akt and GSK3β, neither PI3 kinase nor GSK3β inhibition altered Tys-induced TER elevation. Tys significantly increased Rac1 activity, while inhibition of Rac1 activity significantly attenuated Tys-induced VE-cadherin redistribution and TER elevation. ConclusionJunctional complex, focal adhesion rearrangement and Rac1 activation play critical roles in Tys-mediated barrier protection in pulmonary EC. These results provide mechanistic insights into the effects of this potential ALI therapy.

Melatonin reduces oxidative stress and improves vascular function in pulmonary hypertensive newborn sheep.

Pulmonary hypertension of the newborn (PHN) constitutes a critical condition with severe cardiovascular and neurological consequences. One of its main causes is hypoxia during gestation, and thus, it is a public health concern in populations living above 2500 m. Although some mechanisms are recognized, the pathophysiological facts that lead to PHN are not fully understood, which explains the lack of an effective treatment. Oxidative stress is one of the proposed mechanisms inducing pulmonary vascular dysfunction and PHN. Therefore, we assessed whether melatonin, a potent antioxidant, improves pulmonary vascular function. Twelve newborn sheep were gestated, born, and raised at 3600 meters. At 3 days old, lambs were catheterized and daily cardiovascular measurements were recorded. Lambs were divided into two groups, one received daily vehicle as control and another received daily melatonin (1 mg/kg/d), for 8 days. At 11 days old, lung tissue and small pulmonary arteries (SPA) were collected. Melatonin decreased pulmonary pressure and resistance for the first 3 days of treatment. Further, melatonin significantly improved the vasodilator function of SPA, enhancing the endothelial- and muscular-dependent pathways. This was associated with an enhanced nitric oxide-dependent and nitric oxide independent vasodilator components and with increased nitric oxide bioavailability in lung tissue. Further, melatonin reduced the pulmonary oxidative stress markers and increased enzymatic and nonenzymatic antioxidant capacity. Finally, these effects were associated with an increase of lumen diameter and a mild decrease in the wall of the pulmonary arteries. These outcomes support the use of melatonin as an adjuvant in the treatment for PHN.

Pulmonary vascular and right ventricular reserve in patients with normalized resting hemodynamics after pulmonary endarterectomy.

BackgroundPatients with normalized mean pulmonary artery pressure (mPAP) after pulmonary endarterectomy (PEA) for chronic thromboembolic pulmonary hypertension (CTEPH) do not always regain normal exercise capacity. We evaluated right ventricular function, its interaction with both pulsatile and resistive afterload, and the effect of sildenafil during exercise in these patients.Methods and ResultsFourteen healthy controls, 15 CTEPH patients, and 7 patients with normalized resting mPAP (≤25 mm Hg) post‐PEA underwent cardiopulmonary exercise testing, followed by cardiac magnetic resonance imaging with simultaneous invasive mPAP measurement during incremental supine cycling exercise. Peak oxygen consumption and peak heart rate were significantly reduced in post‐PEA and CTEPH patients compared to controls. The mPAP–cardiac output slope was steeper in post‐PEA patients than in controls and similar to CTEPH. Relative to controls, resting right ventricular ejection fraction was reduced in CTEPH, but not in post‐PEA patients. In contrast, peak exercise right ventricular ejection fraction was reduced both in post‐PEA and CTEPH patients. Exercise led to reduction of pulmonary arterial compliance in all groups. Nevertheless, resting pulmonary arterial compliance values in CTEPH and post‐PEA patients were even lower than those in controls at peak exercise. In post‐PEA patients, sildenafil did not affect resting hemodynamics nor right ventricular function, but decreased the mPAP/cardiac output slope and increased peak exercise right ventricular ejection fraction.ConclusionsExercise intolerance in post‐PEA patients is explained by abnormal pulmonary vascular reserve and chronotropic incompetence. The mPAP/cardiac output slope and pulmonary arterial compliance are sensitive measures demonstrating abnormal resistive and pulsatile pulmonary vascular function in post‐PEA patients. These abnormalities are partially attenuated with sildenafil.

Pulmonary Hypertension in Pregnancy and Anesthetic Implications

Pulmonary hypertension in pregnancy is associated with significant maternal and fetal morbidity and mortality. Although the prognosis seems to be improving as new treatment options have emerged, the physiologic changes that occur during pregnancy and in the peripartum period are still poorly tolerated in this patient population. The main anesthetic implications when caring for a parturient with pulmonary hypertension are related to the dynamic hemodynamic changes that occur during labor and delivery. Hemodynamic goals include avoiding factors that negatively influence the already compromised pulmonary vascular system and right ventricle: reducing pulmonary vascular resistance, maintaining perfusion and function of the right ventricle, and optimizing volume status. Early epidural analgesia plays an important role in attenuating the stress response to labor. Neuraxial anesthesia is frequently preferred over general anesthesia for cesarean deliveries for more controlled speed of onset, degree of autonomic and sensory block, and hemodynamic effects. Pre-delivery planning, timely institution of targeted treatments and an expert multidisciplinary team approach are crucial to achieving successful outcomes in these challenging cases.

Cardiovascular effects of ozone in healthy subjects with and without deletion of glutathione-S-transferase M1

Context: Exposure to ozone has acute respiratory effects, but few human clinical studies have evaluated cardiovascular effects.Objective: We hypothesized that ozone exposure alters pulmonary and systemic vascular function, and cardiac function, with more pronounced effects in subjects with impaired antioxidant defense from deletion of the glutathione-S-transferase M1 gene (GSTM1 null).Methods: Twenty-four young, healthy never-smoker subjects (12 GSTM1 null) inhaled filtered air, 100 ppb ozone and 200 ppb ozone for 3 h, with intermittent exercise, in a double-blind, randomized, crossover fashion. Exposures were separated by at least 2 weeks. Vital signs, spirometry, arterial and venous blood nitrite levels, impedance cardiography, peripheral arterial tonometry, estimation of pulmonary capillary blood volume (Vc), and blood microparticles and platelet activation were measured at baseline and during 4 h after each exposure.Results: Ozone inhalation decreased lung function immediately after exposure (mean ± standard error change in FEV1, air: −0.03 ± 0.04 L; 200 ppb ozone: −0.30 ± 0.07 L; p < 0.001). The immediate post-exposure increase in blood pressure, caused by the final 15-min exercise period, was blunted by 200 ppb ozone exposure (mean ± standard error change for air: 16.7 ± 2.6 mmHg; 100 ppb ozone: 14.5 ± 2.4 mmHg; 200 ppb ozone: 8.5 ± 2.5 mmHg; p = 0.02). We found no consistent effects of ozone on any other measure of cardiac or vascular function. All results were independent of the GSTM1 genotype.Conclusions: We did not find convincing evidence for early acute adverse cardiovascular consequences of ozone exposure in young healthy adults. The ozone-associated blunting of the blood pressure response to exercise is of unclear clinical significance.

Selective depletion of vascular EC-SOD augments chronic hypoxic pulmonary hypertension.

Excess superoxide has been implicated in pulmonary hypertension (PH). We previously found lung overexpression of the antioxidant extracellular superoxide dismutase (EC-SOD) attenuates PH and pulmonary artery (PA) remodeling. Although comprising a small fraction of total SOD activity in most tissues, EC-SOD is abundant in arteries. We hypothesize that the selective loss of vascular EC-SOD promotes hypoxia-induced PH through redox-sensitive signaling pathways. EC-SOD(loxp/loxp) × Tg(cre/SMMHC) mice (SMC EC-SOD KO) received tamoxifen to conditionally deplete smooth muscle cell (SMC)-derived EC-SOD. Mice were exposed to hypobaric hypoxia for 35 days, and PH was assessed by right ventricular systolic pressure measurements and right ventricle hypertrophy. Vascular remodeling was evaluated by morphometric analysis and two-photon microscopy for collagen. We examined cGMP content and soluble guanylate cyclase expression and activity in lung, lung phosphodiesterase 5 (PDE5) expression and activity, and expression of endothelial nitric oxide synthase and GTP cyclohydrolase-1 (GTPCH-1), the rate-limiting enzyme in tetrahydrobiopterin synthesis. Knockout of SMC EC-SOD selectively decreased PA EC-SOD without altering total lung EC-SOD. PH and vascular remodeling induced by chronic hypoxia was augmented in SMC EC-SOD KO. Depletion of SMC EC-SOD did not impact content or activity of lung soluble guanylate cyclase or PDE5, yet it blunted the hypoxia-induced increase in cGMP. Although total eNOS was not altered, active eNOS and GTPCH-1 decreased with hypoxia only in SMC EC-SOD KO. We conclude that the localized loss of PA EC-SOD augments chronic hypoxic PH. In addition to oxidative inactivation of NO, deletion of EC-SOD seems to reduce eNOS activity, further compromising pulmonary vascular function.

Ropivacaine attenuates endotoxin plus hyperinflation-mediated acute lung injury via inhibition of early-onset Src-dependent signaling.

BackgroundAcute lung injury (ALI) is associated with high mortality due to the lack of effective therapeutic strategies. Mechanical ventilation itself can cause ventilator-induced lung injury. Pulmonary vascular barrier function, regulated in part by Src kinase-dependent phosphorylation of caveolin-1 and intercellular adhesion molecule-1 (ICAM-1), plays a crucial role in the development of protein-/neutrophil-rich pulmonary edema, the hallmark of ALI. Amide-linked local anesthetics, such as ropivacaine, have anti-inflammatory properties in experimental ALI. We hypothesized ropivacaine may attenuate inflammation in a “double-hit” model of ALI triggered by bacterial endotoxin plus hyperinflation via inhibition of Src-dependent signaling.MethodsC57BL/6 (WT) and ICAM-1 −/− mice were exposed to either nebulized normal saline (NS) or lipopolysaccharide (LPS, 10 mg) for 1 hour. An intravenous bolus of 0.33 mg/kg ropivacaine or vehicle was followed by mechanical ventilation with normal (7 ml/kg, NTV) or high tidal volume (28 ml/kg, HTV) for 2 hours. Measures of ALI (excess lung water (ELW), extravascular plasma equivalents, permeability index, myeloperoxidase activity) were assessed and lungs were homogenized for Western blot analysis of phosphorylated and total Src, ICAM-1 and caveolin-1. Additional experiments evaluated effects of ropivacaine on LPS-induced phosphorylation/expression of Src, ICAM-1 and caveolin-1 in human lung microvascular endothelial cells (HLMVEC).ResultsWT mice treated with LPS alone showed a 49% increase in ELW compared to control animals (p = 0.001), which was attenuated by ropivacaine (p = 0.001). HTV ventilation alone increased measures of ALI even more than LPS, an effect which was not altered by ropivacaine. LPS plus hyperinflation (“double-hit”) increased all ALI parameters (ELW, EVPE, permeability index, MPO activity) by 3–4 fold compared to control, which were again decreased by ropivacaine. Western blot analyses of lung homogenates as well as HLMVEC treated in culture with LPS alone showed a reduction in Src activation/expression, as well as ICAM-1 expression and caveolin-1 phosphorylation. In ICAM-1 −/− mice, neither addition of LPS to HTV ventilation alone nor ropivacaine had an effect on the development of ALI.ConclusionsRopivacaine may be a promising therapeutic agent for treating the cause of pulmonary edema by blocking inflammatory Src signaling, ICAM-1 expression, leukocyte infiltration, and vascular hyperpermeability.

The pathophysiology of heart failure with preserved ejection fraction

Approximately half of all patients with heart failure have preserved ejection fraction (HFpEF) and, as life expectancies continue to increase in western societies, the prevalence of HFpEF will continue to grow. In contrast to heart failure with reduced ejection fraction (HFrEF), no treatment has been proven in pivotal clinical trials to be effective for HFpEF, largely because of the pathophysiological heterogeneity that exists within the broad spectrum of HFpEF. This syndrome was historically considered to be caused exclusively by left ventricular diastolic dysfunction, but research has identified several other contributory factors, including limitations in left ventricular systolic reserve, systemic and pulmonary vascular function, nitric oxide bioavailability, chronotropic reserve, right heart function, autonomic tone, left atrial function, and peripheral impairments. Multiple individual mechanisms frequently coexist within the same patient to cause symptomatic heart failure, but between patients with HFpEF the extent to which each component is operative can differ widely, confounding treatment approaches. This Review focuses on our current understanding of the pathophysiological mechanisms underlying HFpEF, and how they might be mechanistically related to typical risk factors for HFpEF, including ageing, obesity, and hypertension.

N-acetylcysteine improves established monocrotaline-induced pulmonary hypertension in rats.

BackgroundThe outcome of patients suffering from pulmonary arterial hypertension (PAH) are predominantly determined by the response of the right ventricle to the increase afterload secondary to high vascular pulmonary resistance. However, little is known about the effects of the current available or experimental PAH treatments on the heart. Recently, inflammation has been implicated in the pathophysiology of PAH. N-acetylcysteine (NAC), a well-known safe anti-oxidant drug, has immuno-modulatory and cardioprotective properties. We therefore hypothesized that NAC could reduce the severity of pulmonary hypertension (PH) in rats exposed to monocrotaline (MCT), lowering inflammation and preserving pulmonary vascular system and right heart function.MethodsSaline-treated control, MCT-exposed, MCT-exposed and NAC treated rats (day 14–28) were evaluated at day 28 following MCT for hemodynamic parameters (right ventricular systolic pressure, mean pulmonary arterial pressure and cardiac output), right ventricular hypertrophy, pulmonary vascular morphometry, lung inflammatory cells immunohistochemistry (monocyte/macrophages and dendritic cells), IL-6 expression, cardiomyocyte hypertrophy and cardiac fibrosis.ResultsThe treatment with NAC significantly decreased pulmonary vascular remodeling, lung inflammation, and improved total pulmonary resistance (from 0.71 ± 0.05 for MCT group to 0.50 ± 0.06 for MCT + NAC group, p < 0.05). Right ventricular function was also improved with NAC treatment associated with a significant decrease in cardiomyocyte hypertrophy (625 ± 69 vs. 439 ± 21 μm2 for MCT and MCT + NAC group respectively, p < 0.001) and heart fibrosis (14.1 ± 0.8 vs. 8.8 ± 0.1% for MCT and MCT + NAC group respectively, p < 0.001).ConclusionsThrough its immuno-modulatory and cardioprotective properties, NAC has beneficial effect on pulmonary vascular and right heart function in experimental PH.

Pulmonary vascular function in insulin resistance and diabetes.

Insulin resistance and diabetes are current clinical concerns due to their increasing prevalence in western societies and in developing countries. Cardiovascular alterations, affecting both macro- and microcirculation, are among the major causes of illness and premature death within patients with insulin resistance or diabetes. However, the detrimental effects of insulin resistance and diabetes in the lungs are less clinically apparent, or at least masked by the progression of these metabolic diseases on other target organs. Epidemiological and experimental data suggest a link between pulmonary arterial hypertension and diabetes. Thereby, hemodynamic derangements in uncontrolled diabetes or insulin resistance are predisposing factors leading to early pulmonary alterations that in association with a second hit might accelerate the onset of pulmonary vascular disease and pulmonary hypertension. The present article reviewed the current knowledge about the effects of insulin resistance and diabetes in a territory which has received little attention until recently: the pulmonary circulation.

Pulmonary hypertension: NHLBI Workshop on the Primary Prevention of Chronic Lung Diseases.

Pulmonary vascular dysfunction (PVD) precedes the onset of clinical signs and symptoms of pulmonary arterial hypertension (PAH). PAH is defined by the elevation of pulmonary arterial pressure, which often progresses to right ventricular (RV) dysfunction and failure. PAH affects subjects of all ages, and is associated with diverse medical conditions, most of which are rare. Several factors pose immediate challenges to the development of strategies for primary prevention of PAH, including: (1) the idiopathic or primary form of the disease is extremely rare, limiting screening practicality; (2) methods for the detection of preclinical PVD are currently not established; (3) the understanding of determinants of pulmonary vascular growth, structure, and function in normal and PAH states is insufficient; (4) relatively small numbers of "at-risk" subjects are available for long-term studies to accurately assess disease development; and (5) preventative therapies for PVD are lacking. Despite these limitations, leveraging known at-risk patient populations for study, as well as growing progress across multiple disciplines, ranging from systems biology to advanced and more sensitive functional imaging modalities, may facilitate the opportunity to significantly improve primary prevention research and implementation over the next decade.

Rho GTPases in the regulation of pulmonary vascular barrier function

Pulmonary endothelial permeability is an important determinant of vascular adaptation to changes in oxygen tension, blood pressure, levels of growth factors or inflammatory cytokines. The Ras homologous (Rho) family of guanosine triphosphate phosphatases (Rho GTPases), key regulators of the actin cytoskeleton, regulate endothelial barrier function in response to a variety of environmental factors and signalling agents via the reorganization of the actin cytoskeleton, changes in receptor trafficking or the phosphorylation of junctional proteins. This review provides a brief summary of recent knowledge on Rho-GTPase-mediated effects on pulmonary endothelial barrier function and focuses in particular on their role in pulmonary vascular disorders, including pulmonary hypertension, chronic obstructive pulmonary disease, acute lung injury and acute respiratory distress syndrome.

Classical Transient Receptor Potential 1 and 6 Contribute to Hypoxic Pulmonary Hypertension Through Differential Regulation of Pulmonary Vascular Functions

Hypoxic pulmonary hypertension is characterized by increased vascular tone, altered vasoreactivity, and vascular remodeling, which are associated with alterations in Ca 2+ homeostasis in pulmonary arterial smooth muscle cells. We have previously shown that classical transient receptor potential 1 and 6 (TRPC1 and TRPC6) are upregulated in pulmonary arteries (PAs) of chronic hypoxic rats, but it is unclear whether these channels are essential for the development of pulmonary hypertension. Here we found that pulmonary hypertension was suppressed in TRPC1 and TRPC6 knockout ( Trpc1 −/− and Trpc6 −/− ) mice compared with wild-type after exposure to 10% O 2 for 1 and 3 weeks. Muscularization of pulmonary microvessels was inhibited, but rarefaction was unaltered in hypoxic Trpc1 −/− and Trpc6 −/− mice. Small PAs of normoxic wild-type mice exhibited vasomotor tone, which was significantly enhanced by chronic hypoxia. Similar vasomotor tone was found in normoxic Trpc1 −/− PAs, but the hypoxia-induced enhancement was blunted. In contrast, there was minimal vascular tone in normoxic Trpc6 −/− PAs, but the hypoxia-enhanced tone was preserved. Chronic hypoxia caused significant increase in serotonin-induced vasoconstriction; the augmented vasoreactivity was attenuated in Trpc1 −/− and eliminated in Trpc6 −/− PAs. Moreover, the effects of 3-week hypoxia on pulmonary arterial pressure, right ventricular hypertrophy, and muscularization of microvessels were further suppressed in TRPC1-TRPC6 double-knockout mice. Our results, therefore, provide clear evidence that TRPC1 and TRPC6 participate differentially in various pathophysiological processes, and that the presence of TRPC1 and TRPC6 is essential for the full development of hypoxic pulmonary hypertension in the mouse model.

CD4+ T Cells and IFN-γ Are Required for the Development of Pneumocystis-Associated Pulmonary Hypertension

Pulmonary hypertension (PH) is a disease of diverse etiology. Although primary PH can develop in the absence of prior disease, PH more commonly develops in conjunction with other pulmonary pathologies. We previously reported a mouse model in which PH occurs as a sequela of Pneumocystis infection in the context of transient CD4 depletion. Here, we report that instead of the expected Th2 pathways, the Th1 cytokine IFN-γ is essential for the development of PH, as wild-type mice developed PH but IFN-γ knockout mice did not. Because gene expression analysis showed few strain differences that were not immune-function related, we focused on those responses as potential pathologic mechanisms. In addition to dependence on IFN-γ, we found that when CD4 cells were continuously depleted, but infection was limited by antibiotic treatment, PH did not occur, confirming that CD4 T cells are required for PH development. Also, although CD8 T-cells are implicated in the pathology of Pneumocystis pneumonia, they did not have a role in the onset of PH. Finally, we found differences in immune cell phenotypes that correlated with PH, including elevated CD204 expression in lung CD11c(+) cells, but their role remains unclear. Overall, we demonstrate that a transient, localized, immune response requiring IFN-γ and CD4-T cells can disrupt pulmonary vascular function and promote lingering PH.

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Introduction: Mechanical ventilation (MV) may disturb pulmonary vascular efficiency (PVE) and right ventricular function during ARDS. However, reliable continuous tools for monitoring PVE are lacking. Augmentation index (AI) is a pressure waveform (WF) derived parameter inversely related to vascular

Erratum: Rosiglitazone preserves pulmonary vascular function in lambs with increased pulmonary blood flow

Erratum: Rosiglitazone preserves pulmonary vascular function in lambs with increased pulmonary blood flow

Echocardiographic Assessment of the Right Heart in Mice

Transgenic and toxic models of pulmonary arterial hypertension (PAH) are widely used to study the pathophysiology of PAH and to investigate potential therapies. Given the expense and time involved in creating animal models of disease, it is critical that researchers have tools to accurately assess phenotypic expression of disease. Right ventricular dysfunction is the major manifestation of pulmonary hypertension. Echocardiography is the mainstay of the noninvasive assessment of right ventricular function in rodent models and has the advantage of clear translation to humans in whom the same tool is used. Published echocardiography protocols in murine models of PAH are lacking. In this article, we describe a protocol for assessing RV and pulmonary vascular function in a mouse model of PAH with a dominant negative BMPRII mutation; however, this protocol is applicable to any diseases affecting the pulmonary vasculature or right heart. We provide a detailed description of animal preparation, image acquisition and hemodynamic calculation of stroke volume, cardiac output and an estimate of pulmonary artery pressure.

Stress Echocardiography in Regurgitant Valve Disease

Because of its wide availability, low cost, versatility, and clinical use, stress echocardiography has become increasingly recognized as a valuable tool in the assessment of patients with regurgitant valvular heart disease. Exercise testing is favored compared with pharmacological stress testing for risk stratification in asymptomatic patients and can identify what might otherwise be considered as a moderate valve disease. It has been shown to provide insights into exertional symptoms disproportionate to resting hemodynamics in these patients and to facilitate individual risk stratification. Aggravation of valvular regurgitation severity, exercise-induced pulmonary hypertension (PHT), impaired left ventricular (LV) contractile reserve, inducible ischemia, dynamic LV dyssynchrony, and altered exercise capacity, together with the development of symptoms during exercise echocardiography, provide the clinician with straightforward prognostic information, therefore enabling a more accurate definition of the optimal timing of intervention in patients with valvular regurgitation.1,2 In contrast, dobutamine stress echocardiography has little value in cases of valvular regurgitation. Dobutamine infusion is almost systematically associated with a decrease in the severity of regurgitation; however, it might be of interest in the detection of LV contractile reserve and inducible ischemia. The most common form of exercise used in conjunction with echocardiography is immediate postexercise imaging on a treadmill or upright bicycle ergometer. However, semisupine exercise testing on an appropriate tilted table allows continuous echocardiographic monitoring, which represents an advantageous tool for quantifying changes in valvular regurgitation severity, LV function, and pulmonary pressure (Table). This exercise stress echocardiography modality (ie, per-exercise echocardiography) is the most used in Europe, and we strongly suggest this approach in the setting of valvular heart disease to detect evanescent changes. A symptom-limited graded exercise test is recommended, and ≥80% of the age-predicted upper heart rate should be reached in the absence of symptoms. The test is adapted to the clinical conditions …

Antenatal Hypoxia and Pulmonary Vascular Function and Remodeling

This review provides evidence that antenatal hypoxia, which represents a significant and worldwide problem, causes prenatal programming of the lung. A general overview of lung development is provided along with some background regarding transcriptional and signaling systems of the lung. The review illustrates that antenatal hypoxic stress can induce a continuum of responses depending on the species examined. Fetuses and newborns of certain species and specific human populations are well acclimated to antenatal hypoxia. However, antenatal hypoxia causes pulmonary vascular disease in fetuses and newborns of most mammalian species and humans. Disease can range from mild pulmonary hypertension, to severe vascular remodeling and dangerous elevations in pressure. The timing, length, and magnitude of the intrauterine hypoxic stress are important to disease development, however there is also a genetic-environmental relationship that is not yet completely understood. Determining the origins of pulmonary vascular remodeling and pulmonary hypertension and their associated effects is a challenging task, but is necessary in order to develop targeted therapies for pulmonary hypertension in the newborn due to antenatal hypoxia that can both treat the symptoms and curtail or reverse disease progression.

Prognostic evaluation of patients with pulmonary hypertension by combined non-invasive assessment of pulmonary vascular resistance and right ventricular function

Purpose: Several clinical parameters (exercise tolerance, episode of syncope, pericardial effusion, plasma BNP/NT-pro-BNP, right atrial pressure, cardiac index, tricuspid annular plane systolic excursion [TAPSE] in echocardiography) are known to predict prognosis of pulmonary hypertension (PH). However, a simple and useful method of risk stratification in PH patients is lacking. Here we examined whether combined assessment of pulmonary vascular resistance (PVR) and right ventricular (RV) function by echocardiography is useful for stratifying risks in PH patients. Methods: Consecutive 47 subjects with PH (idiopathic; n=11, connective tissue diseases; n=7, lung diseases; n=12, chronic thromboembolic; n=10, and others, age 57±20, 53% females) who underwent echocardiography were enrolled. PVR was estimated by the ratio of tricuspid regurgitation pressure gradient to the time–velocity integral of the right ventricular outflow tract (TRPG/VTI) and TAPSE was determined as an index of RV function. Cardiac event was defined as cardiac death or hospitalization due for progressive heart failure. Results: During a follow-up period (15.5±10.1 months), 6 patients died due to cardiac causes and 10 patients were hospitalized due to progressive right heart failure. Receiver operating characteristic analysis indicated that optimal cutoff values to predict of cardiac events were 3.24 for TRPG/VTI and 16 for TAPSE. Using the two cutoff values, patients were divided into 4 groups; group with TRPG/VTI ≤3.24 and TAPSE ≥16 (group 1, n=17), group with TRPG/VTI >3.24 and TAPSE ≥16 (group 2, n=12), group with TRPG/VTI ≤3.24 and TAPSE 3.24 and TAPSE <16 (group 4, n=13). Cox's proportional hazards model showed that group 4 (hazard ratio [HR] =38.7, 95% CI 4.2-358.0, p=0.001) and group 2 (HR = 9.8, 95% CI 1.0-93.6, p=0.047) had significantly higher incidences of cardiac events than in group 1. HR in group 3 was higher (HR= 4.6, 95% CI 0.3-83.8) than in group 1, though their difference was not statistically significant presumably because the number of patients in group 3 was small. Conclusions: The combined assessment of TRPG/VTI and TAPSE by non-invasive methods is useful for accurately identifying PH patients at great risk for death or progressive right heart failure. The present results confirm that increased PVR and progressive RV dysfunction underlie poor outcome in PH.