Comparison of endothelial biomarkers according to reversibility of pulmonary hypertension secondary to congenital heart disease

Levels of Plasma Endothelin-1, Circulating Endothelial Cells, Endothelial Progenitor Cells, and Cytokines after Cardiopulmonary Bypass in Children with Congenital Heart Disease: Role of Endothelin-1 Regulation

Congenital heart disease (CHD) can be complicated by pulmonary arterial hypertension (PAH). Cardiopulmonary bypass (CPB) for corrective surgery may cause endothelial dysfunction, involving endothelin-1 (ET-1), circulating endothelial cells (CECs), and endothelial progenitor cells (EPCs). These markers can gauge disease severity, but their levels in children's peripheral blood still lack consensus for prognostic value. The aim of our study was to investigate changes in ET-1, cytokines, and the absolute numbers (Ɲ) of CECs and EPCs in children 24 h before and 48 h after CPB surgery to identify high-risk patients of complications. A cohort of 56 children was included: 41 cases with CHD-PAH (22 with high pulmonary flow and 19 with low pulmonary flow) and 15 control cases. We observed that Ɲ-CECs increased in both CHD groups and that Ɲ-EPCs decreased in the immediate post-surgical period, and there was a strong negative correlation between ET-1 and CEC before surgery, along with significant changes in ET-1, IL8, IL6, and CEC levels. Our findings support the understanding of endothelial cell precursors' role in endogenous repair and contribute to knowledge about endothelial dysfunction in CHD.

Extracellular vesicles in venous thromboembolism and pulmonary hypertension

Venous thromboembolism (VTE) is a multifactorial disease, and pulmonary hypertension (PH) is a serious condition characterized by pulmonary vascular remodeling leading with increased pulmonary vascular resistance, ultimately leading to right heart failure and death. Although VTE and PH have distinct primary etiologies, they share some pathophysiologic similarities such as dysfunctional vasculature and thrombosis. In both conditions there is solid evidence that EVs derived from a variety of cell types including platelets, monocytes, endothelial cells and smooth muscle cells contribute to vascular endothelial dysfunction, inflammation, thrombosis, cellular activation and communications. However, the roles and importance of EVs substantially differ between studies depending on experimental conditions and parent cell origins of EVs that modify the nature of their cargo. Numerous studies have confirmed that EVs contribute to the pathophysiology of VTE and PH and increased levels of various EVs in relation with the severity of VTE and PH, confirming its potential pathophysiological role and its utility as a biomarker of disease severity and as potential therapeutic targets.

Pulmonary arterial hypertension in children with congenital heart disease: a deeper look into the role of endothelial progenitor cells and circulating endothelial cells to assess disease severity

Endothelial progenitor cells and circulating endothelial cells have been proposed as useful markers of severity and disease progression in certain vascular diseases, including pulmonary arterial hypertension. Our study focused on evaluating the levels of circulating endothelial progenitor cells and circulating endothelial cells in patients with congenital left-to-right shunts and pulmonary hypertension undergoing definitive repair. Endothelial progenitor cells (identified by simultaneous co-expression of CD45dim, CD34 + and KDR2 + surface antibodies) and circulating endothelial cells (identified by simultaneous co-expression of inherent antibodies CD45-, CD31+, CD146 + and CD105+) were prospectively measured in seventy-four children (including children with Down syndrome), median age six years (2.75-10), with clinically significant left-to-right shunts undergoing transcatheter or surgical repair and compared to thirty healthy controls. Endothelial progenitor cells and, particularly, circulating endothelial cells were significantly higher in children with heart disease and pulmonary arterial hypertension when compared to controls. Endothelial progenitor cells showed significant correlation with pulmonary vascular resistance index when measured both systemically (r = 0.259; p = 0.026) and in the superior vena cava (r = 0.302; p = 0.009). Children with Down syndrome showed a stronger correlation between systemic cellularity and pulmonary vascular resistance index (r = 0.829; p = 0.002). Endothelial progenitor cells were reduced along their transit through the lung, whereas circulating endothelial cells did not suffer any modification across the pulmonary circulation. In children with yet to be repaired left-to-right shunts, endothelial progenitor cells and circulating endothelial cell counts are increased compared to healthy subjects.

Extracellular vesicle-mediated bidirectional communication between heart and other organs

In recent years, a wealth of studies has identified various molecular species released by cardiac muscle under physiological and pathological conditions that exert local paracrine and/or remote endocrine effects. Conversely, humoral factors, principally produced by organs such as skeletal muscle, kidney, or adipose tissue, may affect the function and metabolism of normal and diseased hearts. Although this cross communication within cardiac tissue and between the heart and other organs is supported by mounting evidence, research on the role of molecular mediators carried by exosomes, microvesicles, and apoptotic bodies, collectively defined as extracellular vesicles (EVs), is at an early stage of investigation. Once released in the circulation, EVs can potentially reach any organ where they transfer their cargo of proteins, lipids, and nucleic acids that exert potent biological effects on recipient cells. Although there are a few cases where such signaling was clearly demonstrated, the results from many other studies can only be tentatively inferred based on indirect evidence obtained by infusing exogenous EVs in experimental animals or by adding them to cell cultures. This area of research is in rapid expansion and most mechanistic interpretations may change in the near future; hence, the present review on the role played by EV-carried mediators in the two-way communication between heart and skeletal muscle, kidneys, bone marrow, lungs, liver, adipose tissue, and brain is necessarily limited. Nonetheless, the available data are already unveiling new, intriguing, and ample scenarios in cardiac physiology and pathophysiology.

Pediatric Pulmonary Hypertension: Definitions, Mechanisms, Diagnosis, and Treatment

Pediatric pulmonary hypertension (PPH) is a multifactorial disease with diverse etiologies and presenting features. Pulmonary hypertension (PH), defined as elevated pulmonary artery pressure, is the presenting feature for several pulmonary vascular diseases. It is often a hidden component of other lung diseases, such as cystic fibrosis and bronchopulmonary dysplasia. Alterations in lung development and genetic conditions are an important contributor to pediatric pulmonary hypertensive disease, which is a distinct entity from adult PH. Many of the causes of pediatric PH have prenatal onset with altered lung development due to maternal and fetal conditions. Since lung growth is altered in several conditions that lead to PPH, therapy for PPH includes both pulmonary vasodilators and strategies to restore lung growth. These strategies include optimal alveolar recruitment, maintaining physiologic blood gas tension, nutritional support, and addressing contributing factors, such as airway disease and gastroesophageal reflux. The outcome for infants and children with PH is highly variable and largely dependent on the underlying cause. The best outcomes are for neonates with persistent pulmonary hypertension (PPHN) and reversible lung diseases, while some genetic conditions such as alveolar capillary dysplasia are lethal. © 2021 American Physiological Society. Compr Physiol 11:2135-2190, 2021.

Outcomes of infants and children undergoing surgical repair of ventricular septal defect: a review of the literature and implications for research with an emphasis on pulmonary artery hypertension

BACKGROUND

Pulmonary vascular disease resulting from CHDs may be the most preventable cause of pulmonary artery hypertension worldwide. Many children in developing countries still do not have access to early closure of clinically significant defects, and the long-term outcomes after corrective surgery remain unclear. Focused on long-term results after isolated ventricular septal defect repair, our review sought to determine the most effective medical therapy for the pre-operative management of elevated left-to-right shunts in patients with an isolated ventricular septal defect.

METHODS

We identified articles specific to the surgical repair of isolated ventricular septal defects. Specific parameters included the pathophysiology and pre-operative medical management of pulmonary over-circulation and outcomes.

RESULTS

Studies most commonly focused on histologic changes to the pulmonary vasculature and levels of thromboxanes, prostaglandins, nitric oxide, endothelin, and matrix metalloproteinases. Only 2/44 studies mentioned targeted pharmacologic management to any of these systems related to ventricular septal defect repair; no study offered evidence-based guidelines to manage pulmonary over-circulation with ventricular septal defects. Most studies with long-term data indicated a measurable frequency of pulmonary artery hypertension or diminished exercise capacity late after ventricular septal defect repair.

CONCLUSION

Long-term pulmonary vascular and respiratory changes can occur in children after ventricular septal defect repair. Research should be directed at providing an evidenced-based approach to the medical management of infants and children with ventricular septal defects (and naturally all CHDs) to minimise consequences of pulmonary artery hypertension, particularly as defect repair may occur late in underprivileged societies.

The changing face of pulmonary hypertension diagnosis: a historical perspective on the influence of diagnostics and biomarkers

Pulmonary hypertension is a complex, multifactorial disease that results in right heart failure and premature death. Since the initial reports of pulmonary hypertension in the late 1800s, the diagnosis of pulmonary hypertension has evolved with respect to its definition, screening tools, and diagnostic techniques. This historical perspective traces the earliest roots of pulmonary hypertension detection and diagnosis through to the current recommendations for classification. We highlight the diagnostic tools used in the past and present, and end with a focus on the future directions of early detection. Early detection of pulmonary hypertension and pulmonary arterial hypertension and the proper determination of etiology are vital for the early therapeutic intervention that can prolong life expectancy and improve quality of life. The search for a non-invasive screening tool for the identification and classification of pulmonary hypertension is ongoing, and we discuss the role of animal models of the disease in this search.

Pulmonary hypertension after bone marrow transplantation in children

INTRODUCTION

Pulmonary hypertension is a rare but important cause of mortality after haematopoietic stem cell transplantation (HSCT) in children. This complication is poorly characterised in the literature. We report here a series of children who developed pulmonary hypertension after HSCT.

METHODS

Between January 2008 and December 2015, we retrospectively analysed 366 children who underwent HSCT (age range 0.5-252 months; median 20.3 months). During the post-HSCT course, echocardiography scans motivated by respiratory symptoms identified 31 patients with elevated tricuspid regurgitation velocity (>2.8 m·s^-1), confirmed when possible by right heart catheterisation (RHC).

RESULTS

22 patients had confirmed pulmonary hypertension with mean±sd pulmonary arterial pressure 40.1±10 mmHg (range 28-62 mmHg) and pulmonary vascular resistance 17.3±9.2 Wood Units (range 8-42 Wood Units). Among the 13 responders at reactivity test, only one patient responded to calcium channel blockers. Seven patients (32%) died. 15 pulmonary hypertension patients were alive after a mean±sd follow-up of 6.5±2.3 years (range 2-10 years). All survivors could be weaned off pulmonary hypertension treatment after a median follow-up of 5 months (range 3-16). The delay between clinical symptoms and initiation of pulmonary hypertension therapy was significantly longer in patients who subsequently died (mean±sd 33.5±23 days; median 30 days) than in survivors (mean±sd 7±3 days) (p<0.001).

CONCLUSION

Pulmonary hypertension is a severe complication of HSCT with an underestimated incidence and high mortality. Aggressive and timely up-front combination therapy allowed normalisation of pulmonary pressure and improved survival.

Endothelial microvesicles in hypoxic hypoxia diseases

Hypoxic hypoxia, including abnormally low partial pressure of inhaled oxygen, external respiratory dysfunction-induced respiratory hypoxia and venous blood flow into the arterial blood, is characterized by decreased arterial oxygen partial pressure, resulting in tissue oxygen deficiency. The specific characteristics include reduced arterial oxygen partial pressure and oxygen content. Hypoxic hypoxia diseases (HHDs) have attracted increased attention due to their high morbidity and mortality and mounting evidence showing that hypoxia-induced oxidative stress, coagulation, inflammation and angiogenesis play extremely important roles in the physiological and pathological processes of HHDs-related vascular endothelial injury. Interestingly, endothelial microvesicles (EMVs), which can be induced by hypoxia, hypoxia-induced oxidative stress, coagulation and inflammation in HHDs, have emerged as key mediators of intercellular communication and cellular functions. EMVs shed from activated or apoptotic endothelial cells (ECs) reflect the degree of ECs damage, and elevated EMVs levels are present in several HHDs, including obstructive sleep apnoea syndrome and chronic obstructive pulmonary disease. Furthermore, EMVs have procoagulant, proinflammatory and angiogenic functions that affect the pathological processes of HHDs. This review summarizes the emerging roles of EMVs in the diagnosis, staging, treatment and clinical prognosis of HHDs.

Thrombo-hemorrhagic liability in children with congenital heart diseases

BACKGROUND

The precise mechanisms of the increased incidence of hemostatic abnormalities in congenital heart disease (CHD) have not been determined. The aim of the study was to evaluate some indicators of activation of platelets and vascular endothelial cells in patients with CHD, evaluation of bleeding liability of these patients, and correlation with the clinical presentation of these patients.

METHODS

This work was carried out on 20 patients with cyanotic congenital heart diseases (CCHD), 20 patients with acyanotic congenital heart diseases (ACHD), and 20 healthy children who served as the control group, aged between 1 and 10years. All were subjected to full clinical examination, complete blood count, oxygen saturation, echocardiography, bleeding and coagulation times, PT, PTT, FDPs, plasma soluble P-selectin, E-selectin, and platelet factor 4 (PF4).

RESULTS

There was significant prolongation of PT and PTT, and there was a significant lowering of platelet counts. These results were obtained in CCHD and ACHD, but were more significant in CCHD patients. There was a significant elevation in PF4 (55.0±25.5ng/mL), P-selectin (128.9±42.44ng/dL), and E-selectin (9461.5±1701.24pg/mL) levels in children with CCHD as compared to those with ACHD (PF4, 21±7.94ng/mL; P-selectin, 80.1±13.2ng/mL; E-selectin, 7969.6±2127.5pg/mL), and significant increase in both groups when compared to the control group (PF4, 8.1±4.7ng/mL; P-selectin, 27.83±9.73ng/mL; E-selectin, 6750.00±3204.00pg/mL). There was a significant negative correlation between oxygen saturation, plasma P-selectin (r=-0.865), E-selectin (r=-0.401), and PF4 (r=-0.792) in patients with CCHD.

CONCLUSION

Patients with CHD-both cyanotic and acyanotic-have variable degrees of increased liability for both thrombosis and hemorrhage that represents some sort of adaptation to preserve hemostasis and to protect these patients against the clinical presentation of both thrombosis and bleeding. This is to say that CHD patients have their own point of balance between thrombogenicity and bleeding liability. Wide-scale studies are needed to detect the normal levels of different thrombohemorrhagic parameters of these patients.

Endothelial microparticles are increased in congenital heart diseases and contribute to endothelial dysfunction

Background

We previously demonstrated that endothelial microparticles (EMPs) are increased in mitral valve diseases and impair valvular endothelial cell function. Perioperative systemic inflammation is an important risk factor and complication of cardiac surgery. In this study, we investigate whether EMPs increase in congenital heart diseases to promote inflammation and endothelial dysfunction.

Methods

The level of plasma EMPs in 20 patients with atrial septal defect (ASD), 23 patients with ventricular septal defect (VSD), and 30 healthy subjects were analyzed by flow cytometry. EMPs generated from human umbilical vascular endothelial cells (HUVECs) were injected into C57BL6 mice, or cultured with HUVECs without or with siRNAs targeting P38 MAPK. The expression and/or phosphorylation of endothelial nitric oxide synthase (eNOS), P38 MAPK, and caveolin-1 in mouse heart and/or in cultured HUVECs were determined. We evaluated generation of nitric oxide (NO) in mouse hearts, and levels of tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6) in cultured HUVECs and in mice.

Results

EMPs were significantly elevated in patients with ASD and VSD, especially in those with pulmonary hypertension when compared with controls. EMPs increased caveolin-1 expression and P38 MAPK phosphorylation and decreased eNOS phosphorylation and NO production in mouse hearts. EMPs stimulated P38 MAPK expression, TNF-α and IL-6 production, which were all inhibited by siRNAs targeting P38 MAPK in cultured HUVECs.

Conclusions

EMPs were increased in adult patients with congenital heart diseases and may contribute to increased inflammation leading to endothelial dysfunction via P38 MAPK-dependent pathways. This novel data provides a potential therapeutic target to address important complications of surgery of congenial heart disease.

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-016-1087-2) contains supplementary material, which is available to authorized users.

Genetic testing and blood biomarkers in paediatric pulmonary hypertension. Expert consensus statement on the diagnosis and treatment of paediatric pulmonary hypertension. The European Paediatric Pulmonary Vascular Disease Network, endorsed by ISHLT and DGPK

Childhood-onset pulmonary arterial hypertension (PAH) is considered complex and multifactorial, with relatively poor estimates of the natural history of the disease. Strategies allowing earlier detection, establishment of disease aetiology together with more accurate and sensitive biomarkers could enable better estimates of prognosis and individualise therapeutic strategies. Evidence is accumulating that genetic defects play an important role in the pathogenesis of idiopathic and hereditary forms of PAH. Altogether nine genes have been reported so far to be associated with childhood onset PAH suggesting that comprehensive multigene diagnostics can be useful in the assessment. Identification of disease-causing mutations allows estimates of prognosis and forms the most effective way for risk stratification in the family. In addition to genetic determinants the analysis of blood biomarkers are increasingly used in clinical practice to evaluate disease severity and treatment responses. As in genetic diagnostics, a multiplex approach can be helpful, as a single biomarker for PAH is unlikely to meet all requirements. This consensus statement reviews the current evidence for the use of genetic diagnostics and use of blood biomarkers in the assessment of paediatric patients with PAH.

Role of Biomarkers in the Diagnosis, Risk Assessment, and Management of Pulmonary Hypertension

Pulmonary hypertension is a severe and debilitating disease with no definite cure, and the domain of targeted therapies is a promising field for better management of this severe condition. The disease comprises pulmonary arterial remodeling, hypoxia, endothelial dysfunction, and inflammation, with subsequent organ damage including right heart and liver dysfunction. Biomarkers have a valuable role at different levels of the disease, from diagnosis to risk assessment and management, in order to decrease the burden of the disease in terms of both morbidity and mortality.

Biomarkers for pediatric pulmonary arterial hypertension: challenges and recommendations

Pediatric pulmonary arterial hypertension (PAH) is an uncommon disease that can occur in neonates, infants, and children, and is associated with high morbidity and mortality. Despite advances in treatment strategies over the last two decades, the underlying structural and functional changes to the pulmonary arterial circulation are progressive and lead eventually to right heart failure. The management of PAH in children is complex due not only to the developmental aspects but also because most evidence-based practices derive from adult PAH studies. As such, the pediatric clinician would be greatly aided by specific characteristics (biomarkers) objectively measured in children with PAH to determine appropriate clinical management. This review highlights the current state of biomarkers in pediatric PAH and looks forward to potential biomarkers, and makes several recommendations for their use and interpretation.

Are endothelial microparticles early markers of pulmonary hypertension?

OBJECTIVE

To find out the relation between endothelial microparticles (EMPs), pulmonary arterial stiffness and thickness of pulmonary artery intima media to determine the prognosis of Eisenmenger syndrome and their correlation with echocardiographic and hemodynamic parameters.

METHODS

Sixteen patients with Eisenmenger syndrome and 37 control patients were included. Electron microparticles levels, angiographic and echocardiographic findings were compared.

RESULTS

Thickness of pulmonary arterial intima media and systolic and diastolic diameters of pulmonary artery were found significant in the patient group. CD144 and CD146 EMP values of patient group were statistically high. However, there was not any significant difference in pulmonary arterial strain, elasticity and stiffness. Positive significant relationship was found between pulmonary artery intima media thickness and CD144 in patient group. But there was not any significance between CD 146 and pulmonary artery intimamedia thickness.

CONCLUSIONS

Invasive methods remain as the gold standard for pulmonary hypertension diagnosis, follow-up and treatment, but it is risky and can even be fatal. Our study showed that EMPs, thickness of pulmonary artery intima media and pulmonary stiffness could be novel noninvasive modalities for the follow-up pulmonary hypertensive patients.

Biomarkers for pediatric pulmonary arterial hypertension - a call to collaborate

Therapeutic approaches in pediatric pulmonary arterial hypertension (PAH) are based primarily on clinician experience, in contrast to the evidence-based approach in adults with pulmonary hypertension. There is a clear and present need for non-invasive and objective biomarkers to guide the accurate diagnosis, treatment, and prognosis of this disease in children. The multifaceted spectrum of disease, clinical presentation, and association with other diseases makes this a formidable challenge. However, as more progress is being made in the understanding and management of adult PAH, the potential to apply this knowledge to children has never been greater. This review explores the state of the art with regard to non-invasive biomarkers in PAH, with an eye toward those adult PAH biomarkers potentially suitable for application in pediatric PAH.

Assessment of operability of patients with pulmonary arterial hypertension associated with congenital heart disease

Pulmonary arterial hypertension (PAH) is a common complication of congenital heart disease, and is now predominantly among patients with uncorrected left-to-right shunts. A growing population is characterized by persistent or recurrent PAH after surgical or interventional correction of left-to-right shunts; the latter having a worse prognosis than other forms of PAH associated with congenital heart disease. New treatments for PAH have been shown to be effective in improving PAH exercise capacity and hemodynamics, raising the hope for making previously inoperable congenital heart defects operable and shifting the framework for the assessment of operability. This review focuses on current methods for assessing operability in PAH associated with congenital heart disease, and the possibility of "treat-and-repair" vs. "repair-and-treat" strategies for patients with inoperable or borderline PAH.

Biomarkers in pulmonary hypertension: what do we know?

Pulmonary hypertension (PH) is a hemodynamic condition that has a poor prognosis and can lead to right-sided heart failure. It may result from common diseases such as left-sided heart or lung disease or may present as the rare entity of idiopathic pulmonary arterial hypertension. Biomarkers that specifically indicate the pathologic mechanism, the severity of the disease, and the treatment response would be ideal tools for the management of PH. In this review, markers related to heart failure, inflammation, hemostasis, remodeling, and endothelial cell-smooth muscle cell interaction are discussed, and their limitations are emphasized. Anemia, hypocarbia, elevated uric acid, and C-reactive protein levels are unspecific markers of disease severity. Brain natriuretic peptide and N-terminal fragment of pro-brain natriuretic peptide have been recommended in current guidelines, whereas other prognostic markers, such as growth differentiation factor-15, osteopontin, and red cell distribution width, are emerging. Chemokines of the CC family and matrix metalloproteases have been linked to the vascular pathologic mechanisms, and new markers such as apelin have been described. Circulating endothelial and progenitor cells have received much attention as markers of disease activity, but with controversial findings. A lack of standards for cell isolation and characterization methods and differences in the pathologic mechanisms of the investigated patients may have contributed to the discrepancies. In conclusion, although several promising markers have been identified over the past few years, the development of more specific markers, standardization, and prospective validation are warranted.

Left-to-Right Shunt with Congenital Heart Disease: Single Center Experience

Objective. The objective of this study was to determine the frequency of pulmonary arterial hypertension (PAH) in congenital heart disease (CHD) with an isolated, large left-to-right shunt and to indicate the factors in the development of PAH. Methods. The pressure measurements in the cardiac chambers and the calculations based on the Fick's principle were compared among 3 separate groups of patients, respectively, with PAH, with hyperkinetic pulmonary hypertension (HPH), and with neither PAH nor HPH. Results. PAH was diagnosed in 30 (12.3%) patients, HPH in 35 (14.4%), while 177 (73.1%) were free of either. The highest risk for the development of PAH was found in the presence of perimembranous ventricular septal defect. A statistically significant difference was seen among these groups as to their left atrial pressure (p = 0.005) and the mean pulmonary arterial pressure (PAP_mean; p < 0.001). While a correlation was present between RpI on one hand and age on the other (p = 0.014), a multiple linear regression could not evidence any correlation among age (p = 0.321), gender (p = 0.929). Conclusion. Our findings do not allow establishing a correlation between the duration of the high pulmonary flow and pulmonary vascular resistance increase or PAH development in isolated left-to-right shunts with congenital heart diseases.

A novel flow cytometric approach to distinguish circulating endothelial cells from endothelial microparticles: relevance for the evaluation of endothelial dysfunction

Circulating endothelial cells (CEC) and endothelial microparticles (EMP) are emerging as markers of endothelial repair and activation/apoptosis. Although significant changes in the number of CEC and EMP in pathological conditions have been reported, their reliable identification and quantification still remain a technical challenge. Here, we present a novel methodology for the identification and quantitation of CEC and EMP based on multicolor flow cytometry. Using a lyse/no wash protocol, we observed that in 50 μl of peripheral blood, the large majority of events expressing an endothelial phenotype (CD45-/CD146+/CD34+) are due to non-nucleated particles (DRAQ5-) carrying mitochondrial activity (MitoTracker+) and, therefore, classified as EMP. We enumerated circulating EMP by single platform absolute count in a lyse/no wash four-color flow-cytometric procedure, which allowed the distinction, within the whole endothelial compartment, of EMP derived from endothelial progenitors (CD45-/CD146+/CD34+/CD117+) and from mature endothelial cells (CD45-/CD146+/CD34+/CD117-). A significant increase in both subsets was observed in patients with diabetes mellitus. Thus, this simple and highly reproducible method may be useful for monitoring endothelial dysfunction in clinical settings.

Pulmonary hypertension in congenital shunts

Pulmonary arterial hypertension frequently arises in patients with congenital heart disease. The vast majority present with congenital cardiac shunts. Initially these may manifest as left-to-right (i.e. systemic-to-pulmonary) shunts. The natural history of disease progression involves vascular remodeling and dysfunction that lead to increased pulmonary vascular resistance and, finally, to the development of Eisenmenger's syndrome, which is the most advanced form. The anatomical, pathological and structural abnormalities occurring in the pulmonary circulation of these patients are, to some extent, similar to those observed in other forms of pulmonary arterial hypertension. This understanding has recently led to significant changes in the management of Eisenmenger's syndrome, with the introduction of treatment specifically targeting pulmonary vascular disease. Early closure of the cardiac shunt remains the best way of preventing pulmonary vascular lesions. However, it is still not clear which preoperative parameters predict safe and successful repair, though hemodynamic evaluation is still routinely used for assessment. Postoperative pulmonary hypertension, both in the immediate period after surgical repair and during long-term follow-up, remains a real therapeutic challenge. The clinical situation of a single ventricle with Fontan circulation also presents difficulties when pulmonary vascular lesions are present. This article reviews pulmonary hypertension associated with congenital shunts and discusses a number of the specific problems encountered.