Pulmonary hypertension diagnosed by right heart catheterisation in sickle cell disease

Global prevalence of elevated estimated pulmonary artery systolic pressure in clinically stable children and adults with sickle cell disease: A systematic review and meta-analysis

BACKGROUND

The current study sought to determine the prevalence of elevated estimated pulmonary artery systolic pressure (ePASP) in clinically stable children and adults with sickle cell disease)SCD(worldwide.

METHODS

The studies included were identified through a search of databases such as PubMed, Scopus, Science Direct, Web of Science, and Embase, as well as Google Scholar engine, adhering to specific inclusion and exclusion criteria. Heterogeneity among the primary study results was assessed using the I-squared index, while publication bias was evaluated through funnel plots, Egger's test, and trim and fill analysis. All statistical analyses were conducted using R software, version 4.3.0.

RESULTS

79 primary studies were included, comprising 6,256 children (<18 years old) and 6,582 adults (≥18 years old) with SCD from 22 countries. The prevalence of elevated ePASP was found to be 21.8% (95% confidence interval [CI]: 18.46 to 25.07) in children and 30.6% (95% CI: 27.1 to 34.1) in adults. The prevalence of elevated ePASP among studies with severe SCD genotypes including HbSS and HbS/β0 was found to be 19.45% (95% CI: 14.95 to 23.95) in children and 29.55% (95% CI: 24.21 to 34.89) in adults. Furthermore, sex-specific prevalence among SCD patients with elevated ePASP indicated the highest prevalence in male children at 60.35% (95% CI: 54.82 to 65.88) and adult female patients at 54.41% (95% CI: 47.3 to 61.5). A comparative analysis of the mean values of clinical and laboratory results revealed significant differences in several characteristics, including age, oxygen saturation, hemoglobin levels, fetal hemoglobin, white blood cell counts, platelet counts, and reticulocyte counts between patients with elevated ePASP and those without, in both children and adult SCD populations.

CONCLUSION

Our findings regarding clinically stable SCD patients highlight a high prevalence of elevated ePASP.

Respiratory manifestations of sickle cell disease in children: a comprehensive review for the pediatrician

INTRODUCTION

Sickle cell disease (SCD) is an inherited hemoglobinopathy characterized by the production of sickle hemoglobin, leading to red blood cells sickling and hemolysis in hypoxic conditions. The resulting acute and chronic endothelial inflammation leads to chronic organ damage. Respiratory manifestations in SCD usually start from childhood and represent the leading causes of morbidity and mortality. Nevertheless, they are generally poorly addressed or recognized later in life, often contributing to a more severe course and complications.

AREAS COVERED

This narrative review aims to outline the significant acute and chronic respiratory manifestations in children with SCD, focusing on prevention and clinical management. Compelling issues that need to be addressed in the future are also discussed. We searched the PubMed database for original papers written in English. Age restrictions were set for children (birth to 18 years). No limitations were set for the date and study country.

EXPERT OPINION

Early detection and treatment of respiratory manifestations in SCD should be central to follow-up with patients affected by SCD. Nonetheless, studies are lacking, especially in pediatric age, and there is still no consensus on their management. Further research is strongly needed to accomplish universally accepted guidelines to guarantee patients the best care possible.

Hypercoagulability in hemoglobinopathies: Decoding the thrombotic threat

Beta (β)-thalassemia and sickle cell disease (SCD) are characterized by a hypercoagulable state, which can significantly influence organ complication and disease severity. While red blood cells (RBCs) and erythroblasts continue to play a central role in the pathogenesis of thrombosis in β-thalassemia and SCD, additional factors such as free heme, inflammatory vasculopathy, splenectomy, among other factors further contribute to the complexity of thrombotic risk. Thus, understanding the role of the numerous factors driving this hypercoagulable state will enable healthcare practitioners to enhance preventive and treatment strategies and develop novel therapies for the future. We herein describe the pathogenesis of thrombosis in patients with β-thalassemia and SCD. We also identify common mechanisms underlying the procoagulant profile of hemoglobinopathies translating into thrombotic events. Finally, we review the currently available prevention and clinical management of thrombosis in these patient populations.

Cardiovascular Consequences of Sickle Cell Disease

Background

Sickle cell disease is an inherited blood disorder which can lead to severe complications, particularly in the cardiovascular and respiratory systems, potentially resulting in arrhythmias, pulmonary hypertension (PH), and cardiomegaly. This study aims to investigate the risk of PH and arrhythmias in adult SCD patients.

Methods

Retrospective analysis of medical records from King Abdulaziz University Hospital (KAUH) for patients with SCD aged 15 and above between 2009 and 2021. The study included 517 patients, with echocardiograms and electrocardiograms assessed according to the European Society of Cardiology/the European Respiratory Society (ESC/ERS) guidelines for categorizing PH risk (low, moderate, high) and detecting arrhythmias. Data analysis employed the Statistical Package for the Social Sciences (SPSS), utilizing quantitative and qualitative data representation. Multivariate logistic regression identified independent risk factors with odds ratios at a 95% confidence interval (CI).

Results

Among participants, 50.3% were male, with a total sample average age of 34.45 ± 9.28 years. Results indicated that 1.4% of patients experienced arrhythmias, 3.7% had a moderate PH risk, and 3.3% were classified as high PH risk. Logistic regression revealed significant independent risk factors for PH and arrhythmia in patients with SCD, with chronic kidney disease (CKD) carrying the highest odds (26.4 times higher odds of PH and 15.36 times higher odds of arrhythmias).

Conclusion

Patients with SCD are at risk for developing PH and various arrhythmias but are often underdiagnosed. Key risk factors for PH included CKD, liver cirrhosis, and pre-existing cardiac conditions. Arrhythmias were significantly associated with CKD and pre-existing cardiac conditions. To mitigate these risks, we recommend involving a multidisciplinary healthcare team in the care of adult patients with SCD. Future prospective studies are advised for early detection of PH and arrhythmias in hemoglobinopathy patients, potentially reducing mortality.

Diagnosis and management of chronic thromboembolic pulmonary hypertension (CTEPH) in sickle cell disease: A review

Pulmonary hypertension in sickle cell disease (SCD) is a complex phenomenon resulting from multiple overlapping etiologies, including pulmonary vasoconstriction in the setting of chronic hemolytic anemia, diastolic dysfunction, and chronic thromboembolic disease. The presence of pulmonary hypertension of any cause in SCD confers a significant increase in mortality risk. Evidence to guide the management of patients with sickle cell disease and chronic thromboembolic pulmonary hypertension (CTEPH) is scant and largely the realm of case reports and small case series. Centered on a discussion of a complex young patient with hemoglobin hemoglobin SC who ultimately underwent treatment with pulmonary thromboendarterectomy, we review the available literature to guide management and discuss and overview of treatment of CTEPH in SCD, considering the unique considerations and challenges facing patients suffering from this multisystem disease.

Pulmonary and Systemic Hemodynamics in Patients with Hyperthyroidism

BACKGROUND

There is an association between hyperthyroidism and pulmonary hypertension. However, the prevalence of pulmonary hypertension in hyperthyroidism and the underlying mechanisms are incompletely defined.

METHODS

Consecutive patients with severe hyperthyroidism, mostly due to Graves disease, were included in this single-center study. Echocardiographic assessment of pulmonary hemodynamics was performed at the time of hyperthyroidism diagnosis (baseline) and after normalization of thyroid hormones (follow-up; median 11 months). In a subset of patients, right heart catheterization and noninvasive assessment of central hemodynamics was performed.

RESULTS

Among all 99 patients, 31% had pulmonary hypertension at baseline. The estimated systolic pulmonary artery pressure correlated significantly with the estimated left ventricular filling pressure (E/e'). The invasively measured systolic pulmonary artery pressure correlated well with the estimated systolic pulmonary artery pressure. Cardiac output, E/e', left and right ventricular dimensions were significantly reduced from baseline to follow-up, whereas the estimated pulmonary vascular resistance did not differ. Diastolic blood pressure was significantly higher at follow-up, with no change in systolic blood pressure. The central systolic blood pressure, however, exhibited a trend for a reduction at follow-up, while the pulse wave velocity was significantly lower at follow-up.

CONCLUSIONS

Approximately one-third of patients with hyperthyroidism have evidence of pulmonary hypertension. Our data suggest that an increased cardiac output and left ventricular filling pressure are the main mechanisms underlying the elevated systolic pulmonary artery pressure in hyperthyroidism, whereas there is no evidence of significant pulmonary vascular disease.

Clinical-radiological-pathological correlation in pulmonary hypertension with unclear and/or multifactorial mechanisms

Ever since the second world symposium on pulmonary hypertension (PH) held in Evian, France, in 1998, PH has been classified into five major clinical groups. Group 5 PH includes a variety of distinct conditions with unclear and/or multifactorial underlying pathologies. Management of these patients is challenging as the number of patients within these groups is often small, not all individuals with certain underlying conditions are affected by PH and patients exhibit distinct symptoms due to different underlying diseases. Studies and clinical trials in these groups are largely lacking and mostly restricted to case series and registry reports. Nonetheless, the worldwide burden of group 5 PH is estimated to be significant in terms of the prevalence of some associated diseases. Group 5 PH encompasses six subgroups, including haematological disorders (inherited and acquired chronic haemolytic anaemia and chronic myeloproliferative disorders), systemic disorders (sarcoidosis, pulmonary Langerhans's cell histiocytosis and neurofibromatosis type 1), metabolic disorders (glycogen storage diseases and Gaucher disease), chronic renal failure with or without haemodialysis, pulmonary tumour thrombotic microangiopathy and fibrosing mediastinitis.

Pulmonary hypertension in sickle cell disease

Sickle cell disease (SCD) is a complex genetic disorder that has long challenged both patients and healthcare professionals. One of its chronic and debilitating complications is pulmonary hypertension (PH). SCD-associated PH is often post-capillary, secondary to left heart disease. It can also sometimes be pre-capillary with multiple and often interrelated mechanisms including obstructive remodeling of the pulmonary vascular bed secondary to hemolysis, endothelial dysfunction, thrombosis, hypoxia, or associated risk factors like portal hypertension. Screening symptomatic patients with echocardiographic signs of PH is crucial to determine those who should undergo right heart catheterization, the cornerstone exam to diagnose and categorize patients with PH. The workup following the diagnosis relies on identifying the cause of PH to personalize treatment. Ongoing efforts are made to treat this complex condition, starting with treating the underlying disease with hydroxyurea or chronic blood exchange transfusion. Robust data on the efficacy of PAH-specific therapies are lacking in this specific population. Initiation of such therapies must be made by an expert center after a case-by-case assessment of the benefit-risk ratio according to the phenotype and the mechanisms involved in the development of PH. Efforts are also poured into studying the interventional and medical therapies used on chronic thromboembolic PH for patients presenting with a thrombotic form. The management of those patients requires a multidisciplinary approach, with conjoint efforts from PH and SCD specialists.

[Diagnostic Algorithm and Screening of Pulmonary Hypertension]

The new guidelines for the diagnosis and treatment of pulmonary hypertension include a new diagnostic algorithm and provide specific recommendations for the required diagnostic procedures, including screening methods. These recommendations are commented on by national experts under the auspices of the DACH. These comments provide additional decision support and background information, serving as a further guide for the complex diagnosis of pulmonary hypertension.

Dual-energy computed tomography to detect early pulmonary vascular changes in children with sickle cell disease: a pilot study

Introduction

Pulmonary hypertension (PH) is a rare but fatal complication of sickle cell disease (SCD) that is possibly reversible if treated early. Dual-energy computed tomography (DECT) is a valuable tool for diagnosing PH. We attempted to determine if DECT can detect early signs of PH in children with SCD.

Methods

This prospective observational pilot study was conducted at the Geneva University Hospitals and was approved by the local human ethics committee (CCER 2019-01975). A written informed consent was obtained from the patients and/or their legal guardian. Eight children (consisting of five girls and three boys) with homozygous SCD were included in the study. They underwent full cardiological workup using transthoracic echocardiography (TTE) and cardiopulmonary exercise test (CPET), as well as DECT.

Results

The median age of the children was 11 years old (range 8-12). All patients exhibited a normal biventricular systo-diastolic function using the TTE. The median tricuspid regurgitant jet velocity value was 2.24 m/s (range 1.96-2.98). Four children were found to have signs of vasculopathy detected on DECT. Of them, two had abnormal screening test results. They both had an increased VE/VCO2 slope during CPET and an increased TVR of >2.5 m/s on TTE.

Conclusion

DECT is capable of identifying early signs of pulmonary vascular disease in children with SCD. Further studies are needed to understand the correlation between DECT abnormalities and hemodynamic pulmonary circulation better.

Sickle Cell Disease and the Heart.. [DOI: 10.21203/rs.3.rs-3040535/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0]

Purpose The objective of this study was to explore the relationship between cardiac structure, cardiac index (CI), and diastolic function parameters, and laboratory values in patients with Sickle Cell Disease (SCD), and to characterize the distinct SCD cardiomyopathy phenotype Methods We conducted a retrospective review of 202 adult patients with SCD (mean age 41.02 ± 13.36) at our hospital who underwent outpatient echocardiographic screening from 2019–2022. Results Our study identified cardiac hypertrophy, chamber dilatation with preserved ejection fraction, elevated TRV, increased cardiac output, and diastolic dysfunction as defining echocardiographic features in SCD. There was a negative correlation between CI and lateral e’ (R = -0.182, P = 0.012), and a positive correlation between CI and E/e’ (R = 0.274, P = 0.0001). Conclusions Our study identified a unique cardiomyopathy in patients with SCD characterized by cardiac hypertrophy with preserved systolic function, abnormal mitral inflow patterns, and elevated cardiac output. These features are indicative of restrictive physiology, as evidenced by left atrial enlargement and diastolic dysfunction, superimposed on hyperdynamic physiology. Further research is needed to elucidate the pathophysiological mechanisms underlying these observations and determine their prognostic significance in vulnerable populations with an elevated burden of cardiovascular disease, including the risk of sudden cardiac death.

[Lung manifestations of sickle-cell disease]

Sickle-cell disease is an autosomal recessive genetic disorder of hemoglobin that causes systemic damage. Hypoxia is the main actor of sickle-cell disease. It initiates acutely the pathogenic cascade leading to tissue damages that in turn induce chronic hypoxia. Lung lesions represent the major risk of morbidity and mortality. Management of sickle-cell disease requires a tight collaboration between hematologists, intensivists and chest physicians. Recurrent episodes of thrombosis and hemolysis characterize the disease. New therapeutic protocols, associating hydroxyurea, transfusion program and stem cell transplantation in severe cases allow a prolonged survival until the fifth decade. However, recurrent pain, crisis, frequent hospital admissions due to infection, anemia or acute chest syndrome and chronic complications leading to organ deficiencies degrade the patients' quality of life. In low-income countries where the majority of sickle-cell patients are living, the disease is still associated with a high mortality in childhood. This paper focuses on acute chest syndrome and chronic lung manifestations.

Prevalence and predictors of non-rheumatic valvular heart disease in patients with sickle cell disease: insights from the National In-Patient Database in 2016 and 2017

Sickle cell disease (SCD) life expectancy has increased in high-income countries, approaching the fifth decade in the United States. Aging in SCD has raised concerns about chronic organ damage due to adaptative and maladaptive cardiac remodeling. This study aims to assess the prevalence and predictors of non-rheumatic valvular heart disease (NRVHD) in SCD patients using the United States National Inpatient Sample database from 2016 and 2017. We conducted a weighted analysis on SCD patients during their index hospitalization. We obtained the prevalence of NRVHD and calculated adjusted odds ratios to identify the associated demographic, social, and clinical characteristics using multivariable logistic regression. We identified 192,460 SCD admissions during 2016 and 2017. Of them, 2450 (1.3%) had NRVHD. Mitral insufficiency (MI) was the most common NRVHD present in 52% of the cases. Mitral valve prolapse represented 12.4%, while aortic stenosis and aortic insufficiency in 10.8% and 12.7%, respectively. Right-sided NRVHD had a lower prevalence, with 17.1% of patients having tricuspid insufficiency (TI) and 6.3% pulmonary insufficiency. There were no cases of mitral, tricuspid, or pulmonary stenosis. Characteristics associated with the presence of NRVHD in SCD were secondary pulmonary hypertension, congestive heart failure, chronic kidney disease, and female sex. NRVHDs, especially MI and TI, are comorbidities in SCD. Literature is scarce on this topic. The predictors found for its occurrence could help address modifiable factors that can positively affect patients with SCD who, due to the natural history of the disease, are at risk of developing NRVHD.

The Cardiopulmonary Complications of Sickle Cell Disease

Sickle cell disease (SCD) is a genetic hemoglobinopathy associated with extensive morbidity and early mortality. While there have been recent improvements in available disease-modifying therapies for SCD, cardiopulmonary complications remain a major risk factor for death in this population. We provide an overview of current knowledge regarding several of the major acute and chronic cardiopulmonary complications in SCD, including: acute chest syndrome, airway disease, lung function abnormalities, nocturnal hypoxemia and sleep disordered breathing, pulmonary vascular disease, and sickle cell cardiomyopathy.

The obstetric implications of pulmonary hypertension and lung transplant

Pulmonary hypertension (PH) is present when the mean pulmonary artery pressure is elevated to >20 mmHg as determined by right heart catheterization. It is categorized into five groups according to the underlying causes. Its presence is considered a contraindication to pregnancy for which therapeutic termination is usually advised due to grave maternal prognosis and pregnancy outcome. Nevertheless, pregnancies in affected women are increasingly reported, about half of which were unplanned, and two-thirds resulted in live births without increased foetal anomalies, notwithstanding increased risks of preterm birth, low birth weight, pre-eclampsia, other obstetric complications, and medical comorbidities, when managed under a multidisciplinary team in specialized centres. Successful lung transplant, the ultimate treatment for PH and other progressive lung diseases, restores fertility, and pregnancy is increasingly encountered, but there is a higher risk of graft rejection and mortality, compared with recipients of other organs. Preconception assessment is vital in optimizing maternal and pregnancy outcomes.

Dimethyl Sulfoxide Induces Hemolysis and Pulmonary Hypertension

Vascular and lung injury are well established complications associated with hemolytic disorders, and hemolysis associated pulmonary hypertension (PH) has emerged as the most serious complication of sickle cell disease. The causal relationship between intravascular hemolysis and the development of PH is still under investigation. Previously we have shown that repetitive administration of hemolyzed autologous blood causes PH in rats. Dimethyl sulfoxide (DMSO), a widely used solvent and anti-inflammatory agent, induces hemolysis in vivo. We hypothesized that repetitive administration of DMSO would induce PH in rats. We also examined hemolysis-induced release of adenosine deaminase (ADA) and arginase from red blood cells, which may amplify hemolysis-mediated vascular injury. Acute administration of DMSO (1.5ml/30 min into the right atrium) induced intravascular hemolysis and pulmonary vasoconstriction. DMSO-induced increase in right ventricular peak systolic pressure (RVPSP) was associated with increased release of ADA. Notably, the acute increase in RVPSP was attenuated by administration of an adenosine A2A receptor agonist or by pretreatment of animals with ADA inhibitor erythro-9-(2-hydroxy-3-nonyl) adenine (EHNA). Repetitive administration of DMSO for 10 days produced anemia, hemoglobinuria, hemoglobinemia, splenomegaly, and development of PH. Histopathological analysis revealed pulmonary vascular remodeling. The presented data describe a new model of hemolysis induced PH, suggesting that hemolysis is mechanistically related to pulmonary hypertension, and pointing to a potential pathogenic role that adenosine deaminase and accelerated adenosine metabolism may play in hemolysis associated pulmonary hypertension.

Sickle Cell Disease and Its Respiratory Complications

Sickle cell disease (SCD) is a hematological disorder that is inherited in an autosomal recessive (AR) fashion. It is caused by mutations in the genes encoding for the globin apoprotein of hemoglobin (Hb), leading to diminished oxygen-carrying ability. Its pathophysiologic mechanism affects multiple organ systems, making it crucial to understand the complications of SCD and find the best ways to prevent and treat them. Some important ways that SCD manifests in the respiratory system are acute chest syndrome (ACS), pulmonary hypertension (PH), asthma, and venous thromboembolism (VTE). This article summarizes their salient features, including pathogenesis related to the adverse outcomes, screening practices, and management guidelines, with the intent to provide greater insight into forming better practices that increase the quality of life in SCD patients.

Exercise Capacity and Biomarkers Among Children and Adolescents With Sickle Cell Disease

BACKGROUND

Sickle cell disease is the most common genetic hemoglobinopathy globally and systemically affects body functioning, decreasing exercise capacity.

OBJECTIVE

To assess exercise capacity through the 6-minute walk test (6MWT) and biomarkers in children and adolescents with sickle cell disease.

MATERIALS AND METHODS

Cross-sectional study involving 20 children and adolescents from Brazil. Demographic and socioeconomic data were obtained. Baseline measurements included biomarkers (red blood cells, hemoglobin, hematocrit, white blood cells, platelets, reticulocytes, lactate dehydrogenase, creatine phosphokinase, C-reactive protein, interleukin 6, and fetal hemoglobin). The following data were obtained before, during, and after the 6MWT: heart rate, blood pressure, and peripheral oxygen saturation.

RESULTS

Eighteen children and adolescents ages 5-14 years old were analyzed, 61.1% boys, 100% black or brown, and 61.1% in primary education, with low household income. The average distance walked in 6MWT was 463.8 (137.7) m, significantly less than the predicted value (P < .001). The distance of 6MWT was associated positively with age (P = .042) and inversely with reticulocyte count (P = .42) and interleukin 6 (P = .00). Age modified the effect of interleukin 6 in younger children (P = .038).

CONCLUSION

Our findings suggest increased baseline levels of biomarkers of hemolysis and inflammation impact on 6MWT performance.

Economic burden of sickle cell disease in Brazil

Background

Sickle cell disease (SCD) may cause several impacts to patients and the whole society. About 4% of the population has the sickle cell trait in Brazil, and 60,000 to 100,000 have SCD. However, despite recognizing the significant burden of disease, little is known about SCD costs.

Objective

To estimate SCD societal costs based on disease burden modelling, under Brazilian societal perspective.

Methods

A disease burden model was built considering the societal perspective and a one-year time horizon, including direct medical and indirect costs (morbidity and mortality). The sum of life lost and disability years was considered to estimate disability-adjusted life years (DALYs). Data from a public database (DATASUS) and the prevalence obtained from literature or medical experts were used to define complications prevalence and duration. Costs were defined using data from the Brazilian public healthcare system table of procedures and medications (SIGTAP) and the human capital method.

Results

Annual SCD cost was 413,639,180 USD. Indirect cost accounted for the majority of burden (70.1% of the total; 290,158,365 USD vs 123,480,816 USD). Standard of care and chronic complications were the main source of direct costs among adults, while acute conditions were the main source among children. Vaso-occlusive crisis represented the complication with the highest total cost per year in both populations, 11,400,410 USD among adults and 11,510,960 USD among children.

Conclusions

SCD management may impose an important economic burden on Brazilian society that may reach more than 400 million USD per year.

High risk and low prevalence diseases: Acute chest syndrome in sickle cell disease

INTRODUCTION

Acute chest syndrome (ACS) in sickle cell disease (SCD) is a serious condition that carries with it a high rate of morbidity and mortality.

OBJECTIVE

This review highlights the pearls and pitfalls of ACS in SCD, including diagnosis and management in the emergency department (ED) based on current evidence.

DISCUSSION

ACS is defined by respiratory symptoms and/or fever and a new radiodensity on chest imaging in a patient with SCD. There are a variety of inciting causes, including infectious and non-infectious etiologies. Although ACS is more common in those with homozygous SCD, clinicians should consider ACS in all SCD patients, as ACS is a leading cause of death in SCD. Patients typically present with or develop respiratory symptoms including fever, cough, chest pain, and shortness of breath, which can progress to respiratory failure requiring mechanical ventilation in 20% of adult patients. However, the initial presentation can vary. While the first line imaging modality is classically chest radiograph, lung ultrasound has demonstrated promise. Further imaging to include computed tomography may be necessary. Management focuses on analgesia, oxygen supplementation, incentive spirometry, bronchodilators, rehydration, antibiotics, consideration for transfusion, and specialist consultation. Empiric antibiotics that cover atypical pathogens are necessary along with measures to increase oxygen-carrying capacity in those with hypoxemia such as simple transfusion or exchange transfusion.

CONCLUSIONS

An understanding of ACS can assist emergency clinicians in diagnosing and managing this potentially deadly disease.

Altered cardiac reserve is a determinant of exercise intolerance in sickle cell anaemia patients

BACKGROUND

The underlying mechanisms of exercise intolerance in sickle cell anaemia (SCA) patients are complex and not yet completely understood. While latent heart failure at rest could be unmasked upon exercise, most previous studies assessed cardiac function at rest. We aimed to investigate exercise cardiovascular reserve as a potential contributor to exercise intolerance in adult SCA patients.

METHODS

In this observational prospective study, we compared prospectively 60 SCA patients (median age 31 years, 60% women) to 20 matched controls. All subjects underwent symptom-limited combined exercise echocardiography and oxygen uptake (VO₂ ) measurements. Differences between arterial and venous oxygen content (C(a-v)O₂ ) were calculated. Cardiac reserve was defined as the absolute change in cardiac index (Ci) from baseline to peak exercise.

RESULTS

Compared to controls, SCA patients demonstrated severe exercise intolerance (median peakVO₂ , 34.3 vs. 19.7 ml/min/kg, respectively, p < .0001). SCA patients displayed heterogeneously increased Ci from rest to peak exercise (median +5.8, range 2.6 to 10.6 L/min/m²) which correlated with peakVO₂ (r = 0.71, p < .0001). In contrast, the C(a-v)O₂ exercise reserve was homogenously reduced and did not correlate with peakVO₂ (r = 0.18, p = .16). While haemoglobin level and C(a-v)O₂ were similar in SCA subgroups, SCA patients in the lower VO₂ tertile had chronotropic incompetence and left ventricular diastolic dysfunction (left atrial peak longitudinal strain was reduced, and both E/e' ratio and left atrial volume index were increased) and were characterized by a reduced cardiac reserve, +5.0[4.2-5.5] compared to +6.7[5.5-7.8] L/min/m² for the rest of the patient cohort, p < .0001.

CONCLUSIONS

Altered cardiac reserve due to chronotropic incompetence and left ventricular diastolic dysfunction seems to be an important determinant of exercise intolerance in adult SCA patients.

Clinical and physiological characteristics of, medically treated, chronic thromboembolic pulmonary hypertension patients in Saudi Arabia: A single center experience

BACKGROUND

Chronic thromboembolic pulmonary hypertension (CTEPH) is uncommon but well-known sequel of venous thromboembolism (VTE). At present, it is the only potential curable subtype of pulmonary hypertension. The aim of this study is to describe the medically treated-CTEPH patients' characteristics in a single specialized PH center in Saudi Arabia.

METHODS

This study presents demographic, clinical, physiological, and hemodynamic characteristics of medically treated-CTEPH patients in a single PH center, namely Prince Sultan Military Medical City, Riyadh, Saudi Arabia. Both incident and prevalent cases are included.

RESULTS

A total of 20 patients with a confirmed diagnosis of CTEPH were included. Mean age at diagnosis was 43 years with a female preponderance of 75%. Most common presenting symptom was dyspnea (100%) followed by syncope (58%). At diagnosis, a mean of 15 ± 10 months had passed since symptoms onset. About 45% of patients were in WHO functional class IV. At baseline, mean 6-min walk distance was 354.3 meters. Overall, VTE was the most frequent risk factor identified (65% of all patients). Nearly 30% of patients had sickle cell disease. 13 out of 20 patients had radiographic (i.e., computed tomography [CT] pulmonary angiogram) features of chronic thromboembolism. About 75% of patients were found to have distal disease on radiographic imaging. At the time of diagnosis, 7 out of 20 (35%) patients demonstrated right ventricular failure on echocardiography. Mean tricuspid annular plane systolic excursion was 17.7 ± 1.20. Median NT-proBNP levels were found to be 688 pg/ml. Mean diffusing capacity for carbon monoxide was 74.8%.

CONCLUSIONS

Diagnosis of CTEPH was established at a relatively younger age. Majority of patients had advanced but distal disease on radiographic imaging, not amenable to surgery.

Overexpression of Msx1 in Mouse Lung Leads to Loss of Pulmonary Vessels Following Vascular Hypoxic Injury

Pulmonary arterial hypertension (PAH) is a progressive lung disease caused by thickening of the pulmonary arterial wall and luminal obliteration of the small peripheral arteries leading to increase in vascular resistance which elevates pulmonary artery pressure that eventually causes right heart failure and death. We have previously shown that transcription factor Msx1 (mainly expressed during embryogenesis) is strongly upregulated in transformed lymphocytes obtained from PAH patients, especially IPAH. Under pathological conditions, Msx1 overexpression can cause cell dedifferentiation or cell apoptosis. We hypothesized that Msx1 overexpression contributes to loss of small pulmonary vessels in PAH. In IPAH lung, MSX1 protein localization was strikingly increased in muscularized remodeled pulmonary vessels, whereas it was undetectable in control pulmonary arteries. We developed a transgenic mouse model overexpressing MSX1 (MSX1^OE) by about 4-fold and exposed these mice to normoxic, sugen hypoxic (3 weeks) or hyperoxic (100% 02 for 3 weeks) conditions. Under normoxic conditions, compared to controls, MSX1^OE mice demonstrated a 30-fold and 2-fold increase in lung Msx1 mRNA and protein expression, respectively. There was a significant retinal capillary dropout (p < 0.01) in MSX1^OE mice, which was increased further (p < 0.03) with sugen hypoxia. At baseline, the number of pulmonary vessels in MSX1^OE mice was similar to controls. In sugen-hypoxia-treated MSX1^OE mice, the number of small (0-25 uM) and medium (25-50 uM) size muscularized vessels increased approximately 2-fold (p < 0.01) compared to baseline controls; however, they were strikingly lower (p < 0.001) in number than in sugen-hypoxia-treated control mice. In MSX1^OE mouse lung, 104 genes were upregulated and 67 genes were downregulated compared to controls. Similarly, in PVECs, 156 genes were upregulated and 320 genes were downregulated from siRNA to MSX1^OE, and in PVSMCs, 65 genes were upregulated and 321 genes were downregulated from siRNA to MSX1^OE (with control in the middle). Many of the statistically significant GO groups associated with MSX1 expression in lung, PVECs, and PVSMCs were similar, and were involved in cell cycle, cytoskeletal and macromolecule organization, and programmed cell death. Overexpression of MSX1 suppresses many cell-cycle-related genes in PVSMCs but induces them in PVECs. In conclusion, overexpression of Msx1 leads to loss of pulmonary vessels, which is exacerbated by sugen hypoxia, and functional consequences of Msx1 overexpression are cell-dependent.

Cardiovascular phenotypes predict clinical outcomes in sickle cell disease: An echocardiography-based cluster analysis

This study sought to link cardiac phenotypes in homozygous Sickle Cell Disease (SCD) patients with clinical profiles and outcomes using cluster analysis. We analyzed data of 379 patients included in the French Etendard Cohort. A cluster analyses was performed based on echocardiographic variables, and the association between clusters, clinical profiles and outcomes was assessed. Three clusters were identified. Cluster 1 (n = 123) patients had the lowest cardiac output, mild left cardiac cavities remodeling, mild diastolic dysfunction, and higher tricuspid regurgitation velocity (TRV). They were predominantly female and displayed the most altered functional limitation. Cluster 2 (n = 102) patients had the highest cardiac output and the most remodeled cardiac cavities. Diastolic function and TRV were similar to cluster 1. These patients had a higher blood pressure and a severe hemolytic anemia. Cluster 3 (n = 154) patients had mild left cardiac cavities remodeling, normal diastolic function and lowest TRV values. They were younger with the highest hemoglobin value. Right heart catheterization was performed in 94 patients. Cluster 1 (n = 33) included the majority of pre-capillary PH whilst cluster 2 (n = 34) included post-capillary PH. No PH was found in cluster 3 (n = 27). After a follow-up of 11.4 ± 2 years, death occurred in 41 patients (11%). Cluster 2 patients had the worst prognosis with a 19% mortality rate versus 12% in cluster 1 and 5% in cluster 3 (p log-rank = 0.003). Cluster analysis of echocardiography variables identified three hemodynamic and clinical phenotypes among SCD patients, each predicting a different prognosis.

The different facets of sickle cell disease-related pulmonary hypertension

PURPOSE OF REVIEW

Sickle cell disease (SCD), one of the most common genetic diseases in the world, is characterized by repeated episodes of hemolysis and vaso-occlusion. Hemolytic anemia is a risk factor for the development of pulmonary hypertension, and currently SCD-related pulmonary hypertension is classified as World Health Organization group 5 pulmonary hypertension. Patients with SCD-related pulmonary hypertension have unique hemodynamics, multiple comorbidities, and distinct phenotypes that may contribute to the development of pulmonary hypertension.

RECENT FINDINGS

SCD-related pulmonary hypertension is defined as a mean pulmonary artery pressure >20 mmHg, a pulmonary artery occlusion pressure ≤15 mmHg and relatively low pulmonary vascular resistance (>2 Wood units) rather than the traditional definition of ≥3 Wood units, an important distinction due to a baseline high-cardiac output state in the setting of chronic anemia and low vascular resistance. Diastolic dysfunction is frequently identified in this patient population and right heart catheterization is essential to determine if combined pre- and postcapillary pulmonary hypertension is present. Thromboembolism is common among patients with SCD, and screening for chronic thromboembolic pulmonary hypertension is essential. Data regarding advanced therapies are limited. Primary treatment options include targeting correction of their primary hemoglobinopathy as well as aggressive management of underlying comorbid conditions.

SUMMARY

SCD-related pulmonary hypertension is common among patients with SCD and is associated with increased mortality. A high index of suspicion is warranted during evaluation to identify all potential factors that may be contributing to disease.

Sickle cell disease and ventricular myocardial strain: A systematic review

Cardiac disease is the primary cause of death in sickle cell disease (SCD). Cardiac abnormalities begin in childhood and progress throughout life. Right and left ventricular (RV, LV) myocardial strain are early markers of systolic dysfunction but are not well investigated among individuals with SCD. The objectives of this review were to (1) identify all published studies that have evaluated ventricular myocardial strain, (2) summarize their values, and (3) compare findings with those obtained from controls. From search results of four electronic databases-Medline, Embase, Scopus, and Web of Science-42 potential articles were identified, of which 18 articles and 17 studies met eligibility criteria for inclusion. The evaluated studies demonstrate that RV and LV myocardial strain are generally abnormal in individuals with SCD compared with controls, despite having normal ejection/shortening fraction. Myocardial strain has been inconsistently evaluated in this population and should be considered any time an echocardiogram is performed.

Enlarged pulmonary artery on computed tomography and respiratory failure in sickle cell disease acute chest syndrome

Predicting the severity of acute chest syndrome is an important research priority in sickle cell disease. In this retrospective study of patients with acute chest syndrome, an enlarged pulmonary artery on computed tomography was associated with severe respiratory failure defined by the need for either noninvasive or mechanical ventilation.

PPARγ increases HUWE1 to attenuate NF-κB/p65 and sickle cell disease with pulmonary hypertension

Sickle cell disease (SCD)-associated pulmonary hypertension (PH) causes significant morbidity and mortality. Here, we defined the role of endothelial specific peroxisome proliferator-activated receptor γ (PPARγ) function and novel PPARγ/HUWE1/miR-98 signaling pathways in the pathogenesis of SCD-PH. PH and right ventricular hypertrophy (RVH) were increased in chimeric Townes humanized sickle cell (SS) mice with endothelial-targeted PPARγ knockout (SSePPARγKO) compared with chimeric littermate control (SSLitCon). Lung levels of PPARγ, HUWE1, and miR-98 were reduced in SSePPARγKO mice compared with SSLitCon mice, whereas SSePPARγKO lungs were characterized by increased levels of p65, ET-1, and VCAM1. Collectively, these findings indicate that loss of endothelial PPARγ is sufficient to increase ET-1 and VCAM1 that contribute to endothelial dysfunction and SCD-PH pathogenesis. Levels of HUWE1 and miR-98 were decreased, and p65 levels were increased in the lungs of SS mice in vivo and in hemin-treated human pulmonary artery endothelial cells (HPAECs) in vitro. Although silencing of p65 does not regulate HUWE1 levels, the loss of HUWE1 increased p65 levels in HPAECs. Overexpression of PPARγ attenuated hemin-induced reductions of HUWE1 and miR-98 and increases in p65 and endothelial dysfunction. Similarly, PPARγ activation attenuated baseline PH and RVH and increased HUWE1 and miR-98 in SS lungs. In vitro, hemin treatment reduced PPARγ, HUWE1, and miR-98 levels and increased p65 expression, HPAEC monocyte adhesion, and proliferation. These derangements were attenuated by pharmacological PPARγ activation. Targeting these signaling pathways can favorably modulate a spectrum of pathobiological responses in SCD-PH pathogenesis, highlighting novel therapeutic targets in SCD pulmonary vascular dysfunction and PH.

Pulmonary hypertension in majority countries: opportunities amidst challenges

PURPOSE OF REVIEW

Pulmonary hypertension is a deadly disease, the causes of which vary between geographical regions. Eighty four percentage of the world's population lives in majority countries (also called low-income and middle-income countries), yet data on pulmonary hypertension in these settings are proportionally scarce. This article provides a review of pulmonary hypertension in majority countries, focusing in detail on the most common causes in these regions, and highlights contextual challenges faced.

RECENT FINDINGS

Epidemiological data confirms a complex and overlapping array of causes, with pulmonary hypertension because of conditions such as rheumatic heart disease, HIV, schistosomiasis, chronic lung disease and sickle cell disease. Delayed pulmonary hypertension diagnosis remains a concern and is ascribed to a lack of resources and lack of pulmonary hypertension awareness by health professionals. Pulmonary hypertension diagnosis is frequently considered once signs of right heart failure emerge, while echocardiography and right heart catheterization are unavailable in many settings. Accurate data on the prevalence of pulmonary hypertension in many of these regions are needed and could be achieved by establishing and frequent review of national databases where the incident and prevalent pulmonary hypertension cases are captured.

SUMMARY

There is urgent need for pulmonary hypertension advocacy among clinicians in the primary, secondary and tertiary healthcare sectors of majority countries, and validated noninvasive diagnostic algorithms are needed. Increased awareness and early diagnosis are likely to improve outcomes of pulmonary hypertension patients in these regions, and potentially stimulate locally relevant research.

Epidemiology, Pathogenesis, and Clinical Approach in Group 5 Pulmonary Hypertension

Pulmonary hypertension (PH) is recognized to be associated with a number of comorbid conditions. Based on these associations, PH is classified into 5 groups, considering common pathophysiologic drivers of disease, histopathologic features, clinical manifestations and course, and response to PH therapy. However, in some of these associated conditions, these characteristics are less well-understood. These include, among others, conditions commonly encountered in clinical practice such as sarcoidosis, sickle cell disease, myeloproliferative disorders, and chronic kidney disease/end stage renal disease. PH in these contexts presents a significant challenge to clinicians with respect to disease management. The most recent updated clinical classification schemata from the 6th World Symposium on PH classifies such entities in Group 5, highlighting the often unclear and/or multifactorial nature of PH. An in-depth review of the state of the science of Group 5 PH with respect to epidemiology, pathogenesis, and management is provided. Where applicable, future directions with respect to research needed to enhance understanding of the clinical course of these entities is also discussed.

Effects of Red Blood Cell Sickling on Right Ventricular Afterload in vivo

BACKGROUND

Hemolysis in sickle cell disease (SCD) releases cell free hemoglobin, which scavenges nitric oxide (NO), leading to pulmonary vascular vasoconstriction, increased pulmonary vascular resistance (PVR), and the development of PH. However, PVR is only one component of right ventricular (RV) afterload. Whether sickled red blood cells increase the total RV afterload, including compliance and wave reflections, is unclear.

OBJECTIVE

Patients with SCD and pulmonary hypertension (PH) have a significantly increased risk of sudden death compared to patients with SCD alone. Sickled red blood cells (RBCs) are fragile and lyse easily. Here, we sought to determine the acute effects of SCD RBCs and increased cell free hemoglobin on RV afterload.

METHODS

Main pulmonary artery pressures and flows were measured in C57BL6 mice before and after exchanges of whole blood (~200 uL, Hct=45%) with an equal volume of SCD RBCs in plasma (Hct=45%) or cell free hemoglobin (Hb+) in solution. After transfusions, animals were additionally stressed with acute hypoxia (AH; 10% O2).

RESULTS

SCD RBCs increased PVR only compared to control RBCs; cell free hemoglobin increased PVR and wave reflections. These increases in RV afterload increased further with AH.

CONCLUSIONS

The release of cell free hemoglobin from fragile SCD RBCs in vivo increases the total RV afterload and may impair RV function more than the SCD RBCs themselves.

Tricuspid regurgitant jet velocity and myocardial tissue Doppler parameters predict mortality in a cohort of patients with sickle cell disease spanning from pediatric to adult age groups - revisiting this controversial concept after 16 years of additional evidence

Sickle cell disease (SCD) is a monogenic hemoglobinopathy associated with significant morbidity and mortality. Cardiopulmonary, vascular and sudden death are the reasons for the majority of young adult mortality in SCD. To better understand the clinical importance of multi-level vascular dysfunction, in 2009 we assessed cardiac function including tricuspid regurgitant jet velocity (TRV), tissue velocity in systole(S') and diastole (E'), inflammatory, rheologic and hemolytic biomarkers as predictors of mortality in patients with SCD. With up to 9 years of follow up, we determined survival in 95 children, adolescents and adults with SCD. Thirty-eight patients (40%) were less than 21 years old at initial evaluation. Survival and Cox proportional-hazards analysis were performed. There was 19% mortality in our cohort, with median age at death of 35 years. In the pediatric subset, there was 11% mortality during the follow up period. The causes of death included cardiovascular and pulmonary complications in addition to other end-organ failure. On Cox proportional-hazards analysis, our model predicts that a 0.1 m/s increase in TRV increases risk of mortality 3%, 1 cm/s increase in S' results in a 91% increase, and 1 cm/s decrease in E' results in a 43% increase in mortality. While excluding cardiac parameters, higher plasma free hemoglobin was significantly associated with risk of mortality (p=.049). In conclusion, elevated TRV and altered markers of cardiac systolic and diastolic function predict mortality in a cohort of adolescents and young adult patients with SCD. These predictors should be considered when counseling cardiovascular risk and therapeutic optimization at transition to adult providers.

Prognostic value of left ventricular longitudinal strain by speckle-tracking echocardiography in patients with sickle cell disease

Cardiovascular complications have been increasingly detected in patients with sickle cell disease (SCD). Two-dimensional speckle-tracking echocardiography (STE) detects early myocardial changes in a number of pathophysiological processes, which may be useful in SCD. This study was designed to examine the value of STE in predicting clinical outcome in adult patients with SCD. A total of 219 patients, mean age 33 ± 12 years were prospectively enrolled. Several clinical, laboratory and echocardiographic variables including left ventricular global longitudinal strain (LVGLS) by STE were assessed. The endpoint was a composite of the following events: (1) all-cause mortality, (2) three or more acute painful episodes that require hospitalization in one year, (3) acute chest syndrome and (4) hospitalization due to disease complication. The majority of the patients had enlargement of LV and left atrial (LA) with preserved ejection fraction. During the mean follow-up of 30 months, 69 patients (32%) had reached the endpoint, including eight deaths (3.7%). No difference was observed in the parameters of diastolic function comparing the patients with and without events. LVGLS ranged from - 12.25 to - 25.44 (mean - 20.26 ± 2.5), with higher values in the patients who had events compared with those who did not. In the multivariable analysis, higher LVGLS values were associated with adverse events (adjusted OR 1.25; 95% CI 1.04-1.51; p = 0.021), independently of the TR maximal velocity and LV ejection fraction. In patients with SCD, higher LV global longitudinal strain was a predictor of adverse outcome, independently of age, TR velocity and LV function.

Association of HIV infection with clinical and laboratory characteristics of sickle cell disease

BACKGROUND

Sickle cell disease (SCD) is a multisystem disorder characterized by a wide spectrum of clinical manifestations and severity. Studies investigating potential effects of co-morbid human immunodeficiency virus (HIV) and SCD have produced conflicting results, and additional investigations are needed to elucidate whether the interaction between the two disease states might impact both HIV and SCD clinical outcomes. The association of HIV infection with clinical and laboratory characteristics of patients with SCD was assessed.

METHODS

This nested case-control study included individuals with SCD with HIV treated at six Brazilian SCD centers. Clinical and laboratory data were abstracted from medical records. HIV positive participants were compared to age, gender, center, and SCD genotype matched HIV negative participants (ratio 1:4). Individual clinical outcomes as well as a composite outcome of any SCD complication and a composite outcome of any HIV-related complication were compared between the two groups.

RESULTS

Fifteen HIV positive participants were included, 12 (80%) alive and 3 (20%) deceased. Most of the HIV positive patients had HbSS (60%; n = 9), 53% (n = 8) were female, and mean age was 30 ± 13 years. The frequency of individual SCD complications of acute chest syndrome/pneumonia, sepsis/bacteremia, pyelonephritis, ischemic stroke, hemorrhagic stroke, abnormal transcranial Doppler (TCD), and pulmonary hypertension was higher in HIV positive participants when compared to HIV negative, although analyzed individually none were statistically significant. HIV positive participants had significantly higher risk of any SCD complication and of a composite HIV-related complication compared to the HIV negative group (HR = 4.6; 95%CI 1.1-19.6; P = 0.04 and HR = 7.7; 95%CI 1.5-40.2; P = 0.02, respectively). There was a non-significant trend towards higher risk of any infections in participants with HIV positive (HR = 3.5; 95%CI 0.92-13.4; P = 0.07). Laboratory parameters levels were not significantly different in individuals with and without HIV.

CONCLUSIONS

In summary, our study in SCD patients shows that those with HIV have an increased risk of any SCD complication and HIV-related complications, as well as a suggestive but not significantly increased risk of infections.

Focused Update on Pulmonary Hypertension in Children-Selected Topics of Interest for the Adult Cardiologist

Pulmonary hypertensive vascular disease (PHVD), and pulmonary hypertension (PH), which is a broader term, are severe conditions associated with high morbidity and mortality at all ages. Treatment guidelines in childhood are widely adopted from adult data and experience, though big differences may exist regarding aetiology, concomitant conditions and presentation. Over the past few years, paediatric aspects have been incorporated into the common guidelines, which currently address both children and adults with pulmonary hypertension (PH). There are multiple facets of PH in the context of cardiac conditions in childhood. Apart from Eisenmenger syndrome (ES), the broad spectrum of congenital heart disease (CHD) comprises PH in failing Fontan physiology, as well as segmental PH. In this review we provide current data and novel aspects on the pathophysiological background and individual management concepts of these conditions. Moreover, we focus on paediatric left heart failure with PH and its challenging issues, including end stage treatment options, such as mechanical support and paediatric transplantation. PH in the context of rare congenital disorders, such as Scimitar Syndrome and sickle cell disease is discussed. Based on current data, we provide an overview on multiple underlying mechanisms of PH involved in these conditions, and different management strategies in children and adulthood. In addition, we summarize the paediatric aspects and the pros and cons of the recently updated definitions of PH. This review provides deeper insights into some challenging conditions of paediatric PH in order to improve current knowledge and care for children and young adults.

Management of chronic respiratory complications in children and adolescents with sickle cell disease

Sickle cell disease (SCD) is a life-threatening hereditary blood disorder that affects millions of people worldwide, especially in sub-Saharan Africa. This condition has a multi-organ involvement and highly vascularised organs, such as the lungs, are particularly affected. Chronic respiratory complications of SCD involve pulmonary vascular, parenchymal and airways alterations. A progressive decline of lung function often begins in childhood. Asthma, sleep-disordered breathing and chronic hypoxaemia are common and associated with increased morbidity. Pulmonary hypertension is a serious complication, more common in adults than in children. Although there is a growing attention towards respiratory care of patients with SCD, evidence regarding the prognostic meaning and optimal management of pulmonary issues in children with this condition is limited.This narrative review presents state-of-the-art evidence regarding the epidemiology, pathophysiology and therapeutic options for chronic respiratory complications commonly seen in paediatric patients with SCD. Furthermore, it highlights the gaps in the current knowledge and indicates future directions for studies that aim to improve our understanding of chronic respiratory complications in children with SCD.

Cardiomyopathy in Sickle Cell Disease

Sickle cell disease (SCD) is an inherited disorder that occurs due to point mutation in the beta-globin chain resulting in the production of hemoglobin S that tends to become rigid and sickle-shaped under low oxygen concentration. These sickle-shaped red blood cells (RBCs) obstruct the blood vessels leading to reduced blood flow to the organs, causing ischemia and tissue fibrosis. These sickle RBCs being abnormal in shape are frequently sequestered by the spleen, creating a state of chronic anemia in the body. This chronic anemia leads to a high cardiac output state causing cardiac remodeling. To tackle chronic anemia, patients are frequently treated with blood transfusions that makes them more prone to the risk of iron overload (from newly transfused RBCs and iron release from the RBCs that just got sequestered as well as from volume overload) and volume overload causing left ventricular (LV) dilation. The above-mentioned mechanism of cardiac hypertrophy, along with LV dilation together, makes SCD-related cardiomyopathy unique cardiomyopathy with features of restrictive cardiomyopathy with LV dilation. It is interesting to note here that even though there is a presence of LV dilatation, Systolic dysfunction is very uncommon in SCD-related cardiomyopathy.

Mechanisms of Exercise Limitation and Prevalence of Pulmonary Hypertension in Pulmonary Langerhans Cell Histiocytosis

BACKGROUND

Pulmonary Langerhans cell histiocytosis (PLCH) determines reduced exercise capacity. The speculated mechanisms of exercise impairment in PLCH are ventilatory and cardiocirculatory limitations, including pulmonary hypertension (PH).

RESEARCH QUESTION

What are the mechanisms of exercise limitation, the exercise capacity, and the prevalence of dynamic hyperinflation (DH) and PH in PLCH?

STUDY DESIGN AND METHODS

In a cross-sectional study, patients with PLCH underwent an incremental treadmill cardiopulmonary exercise test with an evaluation of DH, pulmonary function tests, and transthoracic echocardiography. Those patients with lung diffusing capacity for carbon monoxide (Dlco) < 40% predicted and/or transthoracic echocardiogram with tricuspid regurgitation velocity > 2.5 m/s and/or with indirect PH signs underwent right heart catheterization.

RESULTS

Thirty-five patients were included (68% women; mean age, 47 ± 11 years). Ventilatory and cardiocirculatory limitations, impairment suggestive of PH, and impaired gas exchange occurred in 88%, 67%, 29%, and 88% of patients, respectively. The limitation was multifactorial in 71%, exercise capacity was reduced in 71%, and DH occurred in 68% of patients. FEV₁ and Dlco were 64 ± 22% predicted and 56 ± 21% predicted. Reduction in Dlco, an obstructive pattern, and air trapping occurred in 80%, 77%, and 37% of patients. FEV₁ and Dlco were good predictors of exercise capacity. The prevalence of PH was 41%, predominantly with a precapillary pattern, and mean pulmonary artery pressure correlated best with FEV₁ and tricuspid regurgitation velocity.

INTERPRETATION

PH is frequent and exercise impairment is common and multifactorial in PLCH. The most prevalent mechanisms are ventilatory, cardiocirculatory, and suggestive of PH limitations.

CLINICAL TRIAL REGISTRATION

ClinicalTrials.gov; No.: NCT02665546; URL: www.clinicaltrials.gov.

Smooth muscle cytochrome b5 reductase 3 deficiency accelerates pulmonary hypertension development in sickle cell mice

Pulmonary and systemic vasculopathies are significant risk factors for early morbidity and death in patients with sickle cell disease (SCD). An underlying mechanism of SCD vasculopathy is vascular smooth muscle (VSM) nitric oxide (NO) resistance, which is mediated by NO scavenging reactions with plasma hemoglobin (Hb) and reactive oxygen species that can oxidize soluble guanylyl cyclase (sGC), the NO receptor. Prior studies show that cytochrome b5 reductase 3 (CYB5R3), known as methemoglobin reductase in erythrocytes, functions in VSM as an sGC heme iron reductase critical for reducing and sensitizing sGC to NO and generating cyclic guanosine monophosphate for vasodilation. Therefore, we hypothesized that VSM CYB5R3 deficiency accelerates development of pulmonary hypertension (PH) in SCD. Bone marrow transplant was used to create SCD chimeric mice with background smooth muscle cell (SMC)-specific tamoxifen-inducible Cyb5r3 knockout (SMC R3 KO) and wild-type (WT) control. Three weeks after completing tamoxifen treatment, we observed 60% knockdown of pulmonary arterial SMC CYB5R3, 5 to 6 mm Hg elevated right-ventricular (RV) maximum systolic pressure (RVmaxSP) and biventricular hypertrophy in SS chimeras with SMC R3 KO (SS/R3KD) relative to WT (SS/R3WT). RV contractility, heart rate, hematological parameters, and cell-free Hb were similar between groups. When identically generated SS/R3 chimeras were studied 12 weeks after completing tamoxifen treatment, RVmaxSP in SS/R3KD had not increased further, but RV hypertrophy relative to SS/R3WT persisted. These are the first studies to establish involvement of SMC CYB5R3 in SCD-associated development of PH, which can exist in mice by 5 weeks of SMC CYB5R3 protein deficiency.

American Society of Hematology 2019 guidelines for sickle cell disease: cardiopulmonary and kidney disease

BACKGROUND

Prevention and management of end-organ disease represent major challenges facing providers of children and adults with sickle cell disease (SCD). Uncertainty and variability in the screening, diagnosis, and management of cardiopulmonary and renal complications in SCD lead to varying outcomes for affected individuals.

OBJECTIVE

These evidence-based guidelines of the American Society of Hematology (ASH) are intended to support patients, clinicians, and other health care professionals in their decisions about screening, diagnosis, and management of cardiopulmonary and renal complications of SCD.

METHODS

ASH formed a multidisciplinary guideline panel that included 2 patient representatives and was balanced to minimize potential bias from conflicts of interest. The Mayo Evidence-Based Practice Research Program supported the guideline development process, including performing systematic evidence reviews up to September 2017. The panel prioritized clinical questions and outcomes according to their importance for clinicians and patients. The panel used the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach, including GRADE evidence-to-decision frameworks, to assess evidence and make recommendations, which were subject to public comment.

RESULTS

The panel agreed on 10 recommendations for screening, diagnosis, and management of cardiopulmonary and renal complications of SCD. Recommendations related to anticoagulation duration for adults with SCD and venous thromboembolism were also developed.

CONCLUSIONS

Most recommendations were conditional due to a paucity of direct, high-quality evidence for outcomes of interest. Future research was identified, including the need for prospective studies to better understand the natural history of cardiopulmonary and renal disease, their relationship to patient-important outcomes, and optimal management.

Clinical phenotypes and outcomes of precapillary pulmonary hypertension of sickle cell disease

Rationale

Precapillary pulmonary hypertension (PH) is a devastating complication of sickle cell disease (SCD). Little is known about the influence of the SCD genotype on PH characteristics.

Objectives

To describe clinical phenotypes and outcomes of precapillary PH due to SCD according to disease genotype.

Methods

A nationwide multicentre retrospective study including all patients with SCD-related precapillary PH from the French PH Registry was conducted. Clinical characteristics and outcomes according to SCD genotype were analysed.

Results

58 consecutive SCD patients with precapillary PH were identified, of whom 41 had homozygous for haemoglobin S (SS) SCD, three had S-β0 thalassaemia (S-β0 thal) and 14 had haemoglobin SC disease (SC). Compared to SC patients, SS/S-β0 thal patients were characterised by lower 6-min walk distance (p=0.01) and lower pulmonary vascular resistance (p=0.04). Mismatched segmental perfusion defects on lung scintigraphy were detected in 85% of SC patients and 9% of SS/S-β0 thal patients, respectively, and 50% of SS/S-β0 thal patients had heterogeneous lung perfusion without segmental defects. After PH diagnosis, 31 patients (53%) received medical therapies approved for pulmonary arterial hypertension, and chronic red blood cell exchange was initiated in 23 patients (40%). Four patients were managed for chronic thromboembolic PH by pulmonary endarterectomy (n=1) or balloon pulmonary angioplasty (n=3). Overall survival was 91%, 80% and 60% at 1, 3 and 5 years, respectively, without influence of genotype on prognosis.

Conclusions

Patients with precapillary PH related to SCD have a poor prognosis. Thrombotic lesions appear as a major component of PH related to SCD, more frequently in SC patients.

In-hospital Outcomes and Characteristics of Heart Failure in Sickle Cell Disease

Sickle cell disease (SCD) predominantly affects African-Americans (AAs) in the United States (US). Due to increasing life expectancy in developed countries, SCD-associated cardiomyopathy is typically seen in adults. The aim of this study was to distinguish hospitalization for this phenotype from traditional heart failure (HF) in AAs. We used the National Inpatient Sample (NIS) database to identify HF hospitalizations in AAs between 2005 and 2014 and stratified them according to SCD status. We compared the characteristics and outcomes before and after matching in a 1:3 ratio for age, gender, insurance, smoking status and admission year. Amongst the 1,195,718 HF admissions in AAs, SCD accounted for 7835. The age (mean ± SD) in the SCD cohort was significantly younger (45.66 ± 13.2) vs non-SCD (64.8 ± 15.2), p<0.001. SCD adults had significantly higher rates of pulmonary hypertension (PH), deep vein thrombosis, and pulmonary embolism while non-SCD adults had higher rates of cardiogenic shock and respiratory failure requiring intubation. The national hospitalization rate for HF in AAs increased from 151 to 257 per million between 2005 and 2011 before declining to 241 per million in 2014. There was a decrease in in-hospital mortality in AAs from 4.8% in 2005 to 3.6% in 2014. We also identified independent predictors of in-hospital mortality in SCD with HF. In conclusion, we described hospitalizations for an emerging heart failure phenotype in AAs. Although there is a national decreasing rate of HF hospitalizations in the US, this may not be reflective of the AA population.

Identifying Clinical and Research Priorities in Sickle Cell Lung Disease. An Official American Thoracic Society Workshop Report

Background: Pulmonary complications of sickle cell disease (SCD) are diverse and encompass acute and chronic disease. The understanding of the natural history of pulmonary complications of SCD is limited, no specific therapies exist, and these complications are a primary cause of morbidity and mortality.Methods: We gathered a multidisciplinary group of pediatric and adult hematologists, pulmonologists, and emergency medicine physicians with expertise in SCD-related lung disease along with an SCD patient advocate for an American Thoracic Society-sponsored workshop to review the literature and identify key unanswered clinical and research questions. Participants were divided into four subcommittees on the basis of expertise: 1) acute chest syndrome, 2) lower airways disease and pulmonary function, 3) sleep-disordered breathing and hypoxia, and 4) pulmonary vascular complications of SCD. Before the workshop, a comprehensive literature review of each subtopic was conducted. Clinically important questions were developed after literature review and were finalized by group discussion and consensus.Results: Current knowledge is based on small, predominantly observational studies, few multicenter longitudinal studies, and even fewer high-quality interventional trials specifically targeting the pulmonary complications of SCD. Each subcommittee identified the three or four most important unanswered questions in their topic area for researchers to direct the next steps of clinical investigation.Conclusions: Important and clinically relevant questions regarding sickle cell lung disease remain unanswered. High-quality, multicenter, longitudinal studies and randomized clinical trials designed and implemented by teams of multidisciplinary clinician-investigators are needed to improve the care of individuals with SCD.

A Growing Population of Older Adults with Sickle Cell Disease

In countries with organized access to health care, survival of patients with sickle cell disease (SCD) has greatly improved, shifting the burden of care from a pediatrician to an internal medicine physician. As a consequence, cumulative disease complications related to chronic vasculopathy are becoming more apparent, adding to organ dysfunction from physiologic aging. The time has come for us to reevaluate the approach to managing the older adult with SCD by putting a greater emphasis on geriatric conditions while proactively considering curative options once previously offered only to younger patients, with comprehensive annual assessments and joint clinics with relevant specialists.