Increased pulmonary artery pressures among adolescents with sickle cell disease

Association of elevated tricuspid regurgitation velocity with cerebrovascular and kidney disease in children with sickle cell disease

BACKGROUND

Tricuspid regurgitation velocity (TRV), measured by echocardiography, is a surrogate marker for pulmonary hypertension. Limited pediatric studies have considered the association between TRV and surrogate markers of end-organ disease.

METHODS

We conducted a cross-sectional study that evaluated the prevalence of elevated TRV ≥2.5 m/s and its associations with renal and cerebrovascular outcomes in children with sickle cell disease (SCD) 1-21 years of age in two large sickle cell cohorts, the University of Alabama at Birmingham (UAB) sickle cell cohort, and the Sickle Cell Clinical Research and Intervention Program (SCCRIP) cohort at St. Jude Children's Research Hospital. We hypothesized that patients with SCD and elevated TRV would have higher odds of having either persistent albuminuria or cerebrovascular disease.

RESULTS

We identified 166 children from the UAB cohort (mean age: 13.49 ± 4.47 years) and 325 children from the SCCRIP cohort (mean age: 13.41 ± 3.99 years) with echocardiograms. The prevalence of an elevated TRV was 21% in both UAB and SCCRIP cohorts. Elevated TRV was significantly associated with cerebrovascular disease (odds ratio [OR] 1.88, 95% confidence interval [CI]: 1.12-3.15; p = .017) and persistent albuminuria (OR 1.81, 95% CI: 1.07-3.06; p = .028) after adjusting for age, sex, treatment, and site.

CONCLUSION

This cross-sectional, multicenter study identifies associations between surrogate markers of pulmonary hypertension with kidney disease and cerebrovascular disease. A prospective study should be performed to evaluate the longitudinal outcomes for patients with multiple surrogate markers of end-organ disease.

Antibiotics for treating acute chest syndrome in people with sickle cell disease

BACKGROUND

The clinical presentation of acute chest syndrome is similar whether due to infectious or non-infectious causes, thus antibiotics are usually prescribed to treat all episodes. Many different pathogens, including bacteria, have been implicated as causative agents of acute chest syndrome. There is no standardized approach to antibiotic therapy and treatment is likely to vary from country to country. Thus, there is a need to identify the efficacy and safety of different antibiotic treatment approaches for people with sickle cell disease suffering from acute chest syndrome. This is an update of a Cochrane Review first published in 2007, and most recently updated in 2015.

OBJECTIVES

To determine whether an empirical antibiotic treatment approach (used alone or in combination):1. is effective for acute chest syndrome compared to placebo or standard treatment;2. is safe for acute chest syndrome compared to placebo or standard treatment;Further objectives are to determine whether there are important variations in efficacy and safety:3. for different treatment regimens,4. by participant age, or geographical location of the clinical trials.

SEARCH METHODS

We searched The Group's Haemoglobinopathies Trials Register, which comprises references identified from comprehensive electronic database searches and handsearching of relevant journals and abstract books of conference proceedings. We also searched the LILACS database (1982 to 23 October 2017), African Index Medicus (1982 to 23 October 2017) and trial registries (23 October 2017).Date of most recent search of the Haemoglobinopathies Trials Register: 10 July 2019.

SELECTION CRITERIA

We searched for published or unpublished randomised controlled trials.

DATA COLLECTION AND ANALYSIS

Each author intended to independently extract data and assess trial quality by standard Cochrane methodologies, but no eligible randomised controlled trials were identified.

MAIN RESULTS

For this update, we were unable to find any randomised controlled trials on antibiotic treatment approaches for acute chest syndrome in people with sickle cell disease.

AUTHORS' CONCLUSIONS

This update was unable to identify randomised controlled trials on efficacy and safety of the antibiotic treatment approaches for people with sickle cell disease suffering from acute chest syndrome. While randomised controlled trials are needed to establish the optimum antibiotic treatment for this condition, we do not envisage further trials of this intervention will be conducted, and hence the review will no longer be regularly updated.

Doppler echocardiographic assessment of pulmonary artery pressure in children with sickle cell anaemia

Background

Pulmonary artery hypertension (PAH) is a known complication of patients with sickle cell disease (SCD). The prevalence of PAH has been reported to be high in children with SCD in developed countries. The mortality rate of patients with SCD who develop PAH is said to be 40% at 24 to 40 months after diagnosis. In Sub-Saharan Africa, particularly Nigeria, where the prevalence of SCD is high, there is a dearth of data on the prevalence of PAH in children with SCD. PAH may be a likely contributor to the unacceptably high mortality rate of children with SCD in Africa. The present study aimed to determine the pattern of pulmonary artery pressure in children with sickle cell anaemia (SCA) aged 1 to 12 years in their steady state using Doppler echocardiography in our environment.

Methods

Analytical, comparative and cross-sectional study. It was carried out at Lagos State University Teaching Hospital (LASUTH) over a period of seven months (31st August 2015 through 31st March 2016). A total of 400 children, aged 1 to 12 years were recruited following parental consent and assent. Two hundred children with SCA in steady state and 200 age and sex matched children with haemoglobin genotype AA who served as controls were studied. All subjects and controls had Doppler echocardiography performed on them by the author. PAH was defined as a pulmonary artery systolic pressure (PASP) of ≥30 mmHg at rest derived from the tricuspid regurgitant velocity (TRV) measured from Doppler echocardiography. This corresponds with TRV value of ≥2.5 m/s.

Results

The prevalence of PAH in children with SCA was 8% (n=16). None of the controls had PAH. The youngest subject with PAH was aged 2 years. The overall mean pulmonary artery pressure of children with SCA was significantly higher than that of controls (18.54±5.81 vs. 13.76±5.71 mmHg, P=0.000). The prevalence of PAH in children with SCA demonstrated an increase in trend with age.

Conclusions

The prevalence of PAH in children with SCA in steady state is high. This complication was noticed as early as the second year of life. It is recommended that all children with SCA should have periodic Doppler echocardiography for early detection of PAH.

A modified noninvasive screening protocol for pulmonary hypertension in children with sickle cell disease-Who should be sent for invasive evaluation?

BACKGROUND

Invasive studies have shown that prevalence and severity of pulmonary hypertension (PH) in patients with sickle cell disease (SCD) tend to be overestimated if based exclusively on Doppler-derived tricuspid regurgitant velocity (TRV) as surrogate noninvasive marker with a cutoff ≥2.5 m/s.

OBJECTIVES

We aimed to better define a subgroup of pediatric SCD patients who should be sent for invasive evaluation of pulmonary artery pressure (PAP) based on a modified echocardiographic PH screening protocol that implements evidence from Doppler-catheter comparative studies.

STUDY DESIGN

Charts of 121 pediatric patients with stable SCD were reviewed regarding echocardiographically assessed risk for elevated PAP/PH and associated clinical characteristics. TRV cutoff was refined at ≥2.9 m/s to avoid overestimating the risk for PH. TRV was combined with additional echocardiographic parameters to avoid underestimating the PH risk.

RESULTS

Ninety-one patients qualified for analysis. Based on our modified echocardiographic protocol, 5.5% of patients qualified for at least moderate risk for elevated PAP (compatible with PH) as opposed to 20.9% if based exclusively on TRV ≥2.5 m/s. These patients were older, homozygous for hemoglobin S (HbSS), and more anemic. No subject had an echocardiographic risk constellation suggesting more than mild PH.

CONCLUSIONS

Our modified noninvasive screening protocol-if confirmed by invasive studies-may help to better identify a subgroup of pediatric SCD patients in whom evaluation by catheterization appears justified. Unlike estimates based on the conventional protocol, the size of the targeted subgroup compares favorably with catheterization-confirmed PH prevalence rates. Characteristics associated with an increased PH risk were also identified.

The global burden of pulmonary hypertension in sickle cell disease: a systematic review and meta-analysis

Elevated tricuspid regurgitant jet velocity (TRJV) is a surrogate measure of pulmonary hypertension (PH) in persons with sickle cell disease (SCD). We sought to estimate the burden of PH in people living with sickle cell disease based on TRJV. From 2000 to 2015, we searched electronic databases for eligible publications and included 29 studies (n = 5358 persons). We used random effects modeling to determine the pooled estimate of elevated TRJV. The overall pooled prevalence of elevated TRJV was 23.5 %(95 % CI 19.5-27.4) in persons with SCD. The pooled prevalence of elevated TRJV in children and adults with SCD was 20.7 % (95 % CI 15.7--25.6) and 24.4 % (95 % CI 18.4-30.4), respectively. TRJV is prevalent among adults and children with SCD. Our finding support international recommendations that call for screening for PH in SCD patients.

Antibiotics for treating acute chest syndrome in people with sickle cell disease

BACKGROUND

The clinical presentation of acute chest syndrome is similar whether due to infectious or non-infectious causes, thus antibiotics are usually prescribed to treat all episodes. Many different pathogens, including bacteria, have been implicated as causative agents of acute chest syndrome. There is no standardized approach to antibiotic therapy and treatment is likely to vary from country to country. Thus, there is a need to identify the efficacy and safety of different antibiotic treatment approaches for people with sickle cell disease suffering from acute chest syndrome. This is an update of a Cochrane review first published in 2007, and previously updated in 2013.

OBJECTIVES

To determine whether an empirical antibiotic treatment approach (used alone or in combination):1. is effective for acute chest syndrome compared to placebo or standard treatment;2. is safe for acute chest syndrome compared to placebo or standard treatment;Further objectives are to determine whether there are important variations in efficacy and safety:3. for different treatment regimens,4. by participant age, or geographical location of the clinical trials.

SEARCH METHODS

We searched The Group's Haemoglobinopathies Trials Register, which comprises references identified from comprehensive electronic database searches and handsearching of relevant journals and abstract books of conference proceedings. We also searched the LILACS database (1982 to 23 February 2015), African Index Medicus (1982 to 23 February 2015). and the World Health Organization International Clinical Trials Registry Platform Search Portal (23 February 2015).Date of most recent search of the Haemoglobinopathies Trials Register: 20 January 2015.

SELECTION CRITERIA

We searched for published or unpublished randomised controlled trials.

DATA COLLECTION AND ANALYSIS

Each author intended to independently extract data and assess trial quality by standard Cochrane Collaboration methodologies, but no eligible randomised controlled trials were identified.

MAIN RESULTS

For this update, we were unable to find any randomised controlled trials on antibiotic treatment approaches for acute chest syndrome in people with sickle cell disease.

AUTHORS' CONCLUSIONS

This update was unable to identify randomised controlled trials on efficacy and safety of the antibiotic treatment approaches for people with sickle cell disease suffering from acute chest syndrome. Randomised controlled trials are needed to establish the optimum antibiotic treatment for this condition.

Elevated tricuspid regurgitant velocity as a marker for pulmonary hypertension in children with sickle cell disease: less prevalent and predictive than previously thought?

Although elevated tricuspid regurgitant velocity (TRV), an echocardiographic marker for pulmonary hypertension, has previously been tied to mortality in adult patients with sickle cell disease, recent data demonstrated that it correlates poorly with catheterization findings. We describe the largest echocardiographic evaluation of pediatric patients with sickle cell disease to date, specifically the results of a protocol whereby a TRV≥250 cm/s prompted further evaluation. We investigated if elevated TRV would independently identify patients at risk for increased morbidity. A clinical echocardiographic database containing 630 patients with sickle cell disease was retrospectively reviewed; 120 patients (19%) met inclusion criteria and were compared 1:1 to randomly selected age-matched controls from the same database. By multivariate analysis, the elevated TRV cohort did not differ from controls in likelihood of acute chest episodes, hospitalization, or stroke. The study cohort's mean TRV in fact decreased to 242±33 cm/s at follow-up without a discernible and comprehensive intervention to explain the improvement. Three patients had catheterization-proven pulmonary hypertension. In conclusion, elevated TRV in children with sickle cell disease is less prevalent than previously thought and is not independently associated with increased short-term morbidity.

Antibiotics for treating acute chest syndrome in people with sickle cell disease

BACKGROUND

The clinical presentation of acute chest syndrome is similar whether due to infectious or non-infectious causes, thus antibiotics are usually prescribed to treat all episodes. Many different pathogens, including bacteria, have been implicated as causative agents of acute chest syndrome. There is no standardized approach to antibiotic therapy and treatment is likely to vary from country to country. Thus, there is a need to identify the efficacy and safety of different antibiotic treatment approaches for people with sickle cell disease suffering from acute chest syndrome.

OBJECTIVES

To determine whether an empirical antibiotic treatment approach (used alone or in combination): 1. is effective for acute chest syndrome compared to placebo or standard treatment; 2. is safe for acute chest syndrome compared to placebo or standard treatment;Further objectives are to determine whether there are important variations in efficacy and safety: 3. for different treatment regimens, 4. by participant age, or geographical location of the clinical trials.

SEARCH METHODS

We searched The Group's Haemoglobinopathies Trials Register, which comprises references identified from comprehensive electronic database searches and handsearching of relevant journals and abstract books of conference proceedings. We also searched the LILACS database (1982 to 19 October 2012), African Index Medicus (1982 to 3 November 2012). and the World Health Organization International Clinical Trials Registry Platform Search Portal (19 October 2012).Date of most recent search of the Haemoglobinopathies Trials Register: 29 October 2012.

SELECTION CRITERIA

We searched for published or unpublished randomised controlled trials.

DATA COLLECTION AND ANALYSIS

Each author intended to independently extract data and assess trial quality by standard Cochrane Collaboration methodologies, but no eligible randomised controlled trials were identified.

MAIN RESULTS

For this update, we were unable to find any randomised controlled trials on antibiotic treatment approaches for acute chest syndrome in people with sickle cell disease.

AUTHORS' CONCLUSIONS

This update was unable to identify randomised controlled trials on efficacy and safety of the antibiotic treatment approaches for people with sickle cell disease suffering from acute chest syndrome. Randomised controlled trials are needed to establish the optimum antibiotic treatment for this condition.

Advances in therapies for pediatric pulmonary arterial hypertension

Pulmonary arterial hypertension (PAH) is a life-threatening disease characterized by progressive obliteration of the pulmonary vasculature, leading to right heart failure and death if left untreated. Prior to the current treatment era, pulmonary hypertension carried a poor prognosis with a high mortality rate, but its prognosis has changed over the past decades in relation to new therapeutic agents. Nevertheless, pulmonary hypertension continues to be a serious condition, which is extremely challenging to manage. The data in children are often limited owing to the small number of patients, and extrapolation from adults to children is not straightforward. While none of these new therapeutic agents have been specifically approved for children, there is evidence that each can appropriately benefit the PAH child. We review the current understanding of pediatric pulmonary hypertension, classification, diagnostic evaluation and available treatment. A description of targeted pharmacological therapy and new treatments in children is outlined.

Left ventricular hypertrophy and diastolic dysfunction in children with sickle cell disease are related to asleep and waking oxygen desaturation

Premature death and cardiac abnormalities are described in individuals with sickle cell disease (SCD), but the mechanisms are not well characterized. We tested the hypothesis that cardiac abnormalities in children with SCD are related to sleep-disordered breathing. We enrolled 44 children with SCD (mean age, 10.1 years; range, 4-18 years) in an observational study. Standard and tissue Doppler echocardiography, waking oxygen saturation averaged over 5 minutes, and overnight polysomnography were obtained in participants, each within 7 days. Eccentric left ventricular (LV) hypertrophy was present in 46% of our cohort. After multivariable adjustment, LV mass index was inversely related to average asleep and waking oxygen saturation. For every 1% drop in the average asleep oxygen saturation, there was a 2.1 g/m(2.7) increase in LV mass index. LV diastolic dysfunction, as measured by the E/E' ratio, was present in our subjects and was also associated with low oxygen saturation (sleep or waking). Elevated tricuspid regurgitant velocity (> or = 2.5 m/sec), a measure of pulmonary hypertension, was not predicted by either oxygen saturation or sleep variables with multivariable logistic regression analysis. These data provide evidence that low asleep and waking oxygen saturations are associated with LV abnormalities in children with SCD.

Pulmonary hypertension in children and young adults with sickle cell disease: evidence for familial clustering

BACKGROUND

Pulmonary hypertension (PHTN) is increasingly recognized as a serious complication of sickle cell disease (SCD). Our objective was to determine the prevalence of PHTN and identify factors associated with PHTN among children and young adults with SCD in Lebanon.

PROCEDURE

From June 2004 to June 2008, 90 patients were studied. Correlation of TRV with LDH, mean corpuscular volume (MCV), fetal hemoglobin (HbF), hydroxyurea use, and G6PD deficiency was performed. Transthoracic Doppler echocardiography was performed during steady-state at each patient's initial visit and yearly thereafter. PHT was defined as a tricuspid regurgitant jet velocity (TRV) > or =2.5 m/sec.

RESULTS

Twenty-seven patients (31.8%) were found to have PHTN. They had significantly higher LDH levels (P = 0.008) and MCV (P = 0.024). There was a higher percentage of patients on hydroxyurea in the group with PHTN (78% vs. 50%, P = 0.015). Furthermore, five children, mean age 9.8 years (range, 6-13 years), with initially normal TRV developed PHTN while on hydroxyurea for at least 3 years, at a mean dose of 19.2 mg/kg/day (range, 14-24). PHTN clustered in families and was found in all members with SCD in 7 of the 21 families studied; they contributed 16 of the 27 patients with PHTN. None of the 21 patients with PHTN were G6PD deficient compared to 4 of 36 without PHTN.

CONCLUSIONS

PHTN was common, associated with increased hemolysis but not G6PD deficiency, and clustered in families. Moreover, PHTN developed despite hydroxyurea therapy in five patients.

Pulmonary hypertension in hemolytic anemias

Pulmonary hypertension (PH) has been reported with nearly all forms of the inherited as well as the acquired hemolytic anemias. Recent research investigating the pathophysiology of PH in sickle cell disease and thalassemia has helped elucidate the central role of hemolysis-mediated endothelial dysfunction in the development of PH in these populations. Although the most appropriate treatment of PH in patients with hemolytic anemia is not clearly defined, the associated significant increased risk of death underscores the need for randomized clinical trials in this area.

Prospective echocardiography assessment of pulmonary hypertension and its potential etiologies in children with sickle cell disease

Pulmonary hypertension (PH) is associated with adverse outcomes in adults with sickle-cell disease (SCD), but its importance in children is less clear. The aim of this study was to define the incidence and causes of PH in pediatric patients with SCD. Children with SCD (n = 310) and matched controls (n = 54) were prospectively enrolled under basal conditions. Participants underwent echocardiography, pulse oximetry, 6-minute walk tests, and hematologic testing. Echocardiographic measures were compared between patients with SCD and control subjects before and after adjusting for hemoglobin. Correlations of echocardiographic and clinical parameters were determined. Tricuspid regurgitation velocity (TRV) was elevated compared to controls (2.28 vs 2.10 m/s, p <0.0001). Increased TRV was associated with left ventricular diastolic diameter, hemoglobin, and estimated left atrial pressure. TRV remained elevated when controlling for left ventricular diameter and left atrial pressure. Echocardiographically derived pulmonary resistance was not significantly different between patients with SCD and controls, although it was elevated in the SCD subgroup with elevated TRV. When controlling for hemoglobin, TRV was no longer statistically different, but pulmonary insufficiency velocity, septal wall thickness, and estimated pulmonary resistance were statistically higher. TRV, pulmonary insufficiency end-diastolic velocity, and markers of increased cardiac output were correlated with indicators of adverse functional status, including history of acute chest syndrome, stroke, transfusions, and 6-minute walk distance. In conclusion, children with SCD had mildly increased TRV that was correlated with increased cardiac output and left ventricular filling pressures. Hemoglobin-adjusted analysis also suggested a contribution of primary vascular changes.

Tricuspid regurgitant jet velocity elevation and its relationship to lung function in pediatric sickle cell disease

Concerns about the morbidity and mortality associated with tricuspid regurgitant jet velocity (TRJV) elevation, which may indicate pulmonary hypertension (PHT), in adults with sickle cell disease (SCD) have prompted growing interest in screening the pediatric sickle cell population. The goals of our study were to estimate the prevalence of TRJV elevation and determine its relationship to pulmonary function in children and young adults with SCD at baseline. Seventy-eight subjects (10-24 years old) with SCD underwent prospective screening by Doppler echocardiogram (ECHO), complete lung function evaluation, and laboratory testing as part of standard care at steady state. Tricuspid regurgitation was quantifiable in 68/78 (87%) subjects and peak TRJV was > or =2.5 m/sec in 26/78 (33.3%) evaluated. The frequency of obstruction, restriction, or abnormal gas exchange found on lung function evaluation was not significantly different in subjects with and without TRJV elevation. However, significant inverse correlations were observed between TRJV and both % predicted forced vital capacity (FVC) (r = -0.29, P = 0.022) and oxygen saturation (r = -0.26, P = 0.036). When compared to subjects without TRJV elevation, subjects with TRJV elevation had significantly lower % predicted forced expiratory volume in 1 sec (FEV(1)) (78.9 +/- 14.4 vs. 86.6 +/- 13.0%, P = 0.023), FVC (82.8 +/- 14.1 vs. 90.7 +/- 12.9%, P = 0.017), and oxygen saturation (95.8 +/- 3.2 vs. 97.5 +/- 2.4%, P = 0.016). We found that the combination of low hemoglobin and low % predicted FVC best predicted TRJV elevation (chi(2) = 17.05, P = 0.001) in our cohort, correctly identifying 70% of cases and resulting in positive and negative predictive values of 60 and 74%, respectively. We conclude that in this young population with SCD, TRJV elevation that is not significantly associated with abnormal lung function is common at baseline.

Nitric oxide and arginine dysregulation: a novel pathway to pulmonary hypertension in hemolytic disorders

Secondary pulmonary hypertension (PH) is emerging as one of the leading causes of mortality and morbidity in patients with hemolytic anemias such as sickle cell disease (SCD) and thalassemia. Impaired nitric oxide (NO) bioavailability represents the central feature of endothelial dysfunction, and is a major factor in the pathophysiology of PH. Inactivation of NO correlates with hemolytic rate and is associated with the erythrocyte release of cell-free hemoglobin, which consumes NO directly, and the simultaneous release of the arginine-metabolizing enzyme arginase, which limits bioavailability of the NO synthase substrate arginine during the process of intravascular hemolysis. Rapid consumption of NO is accelerated by oxygen radicals that exists in both SCD and thalassemia. A dysregulation of arginine metabolism contributes to endothelial dysfunction and PH in SCD, and is strongly associated with prospective patient mortality. The central mechanism responsible for this metabolic disorder is enhanced arginine turnover, occurring secondary to enhanced plasma arginase activity. This is consistent with a growing appreciation of the role of excessive arginase activity in human diseases, including asthma and pulmonary arterial hypertension. New treatments aimed at improving arginine and NO bioavailability through arginase inhibition, suppression of hemolytic rate, oral arginine supplementation, or use of NO donors represent potential therapeutic strategies for this common pulmonary complication of hemolytic disorders.

A prospective appraisal of pulmonary hypertension in children with sickle cell disease

OBJECTIVES

Pulmonary hypertension (PHT) is a life-threatening complication of sickle cell disease that occurs in 20% to 40% of adults. Measurement of maximal tricuspid regurgitant jet velocity (TRV) by echocardiography provides a noninvasive screening tool; TRV values > or =2.5 m/s are correlated with PHT and increased mortality. Our objective was to estimate the prevalence of PHT in our pediatric sickle cell population and its possible association with various clinical and laboratory findings, including obstructive sleep apnea and/or pulmonary dysfunction.

STUDY DESIGN

Eligible children had measurement of the TRV. Clinical data were collected, including detailed history with a standardized sleep apnea questionnaire; those with suggestive histories had polysomonography. Pulmonary function was assessed using whole body plethysmography.

RESULTS

Of 48 subjects (79% homozygous sickle cell anemia; median age 12 y; 11 receiving chronic transfusion) enrolled in the study, 4 (8.3%) had TRV >2.5 m/s; all had homozygous sickle cell anemia and 1 was receiving hydroxyurea after 3 years of transfusion for secondary stroke prevention. Subjects with elevated TRV had higher indirect bilirubin levels; we found no association between elevated TRV and obstructive apnea or pulmonary function abnormalities.

CONCLUSIONS

Elevation of TRV was relatively uncommon in our pediatric patients as compared with prevalence reported in adults and may be associated with increased hemolysis. There was no association with obstructive sleep apnea or abnormal pulmonary function.

Pulmonary arterial hypertension in children: a medical update

Pulmonary arterial hypertension (PAH) is a life-threatening disease characterized by a progressive pulmonary vasculopathy with ensuing right heart failure if left untreated. In the 1980's, prior to the current treatment era, idiopathic pulmonary arterial hypertension (IPAH) carried a poor prognosis with a 10 month median survival for children after diagnosis. However, in 1995 continuous intravenous epoprostenol was approved for the treatment of severe PAH, improving hemodynamics, quality of life, exercise capacity, functional class and survival. In the past decade there have been further advances in the treatment of PAH; however, there is still no cure. While much of the groundbreaking clinical research has been performed in adults, children have also seen the benefits of PAH novel therapies. The target population among pediatric patients is expanding with the recent recognition of pulmonary hypertension as a risk factor for sickle cell disease patients. With rapid advances, navigating the literature becomes challenging. A comprehensive review of the most recent literature over the past year on available and emerging novel therapies as well as an approach to target pediatric populations provides insights into the management of pediatric PAH patients.

Longitudinal follow up of elevated pulmonary artery pressures in children with sickle cell disease

Elevated pulmonary artery pressures (PAP) occur in approximately 30% of children with sickle cell disease. In adults, pulmonary hypertension is significantly associated with mortality. There are no data on the long term significance in children. Nineteen children with SS/Sbeta(0) thalassaemia had elevated PAP, defined as tricuspid regurgitant jet velocity (TRV) > or =2.5 m/s on screening echocardiograms. They were prospectively followed for 23 months (range 19-31 months). Patients with initial TRV > or = 3 or TRV > or = 2.5 m/s on repeat echocardiogram had cardiopulmonary evaluation and were offered treatment with hydroxyurea. Associated conditions like asthma and obstructive sleep apnea were treated. 18/19 patients had follow-up echocardiograms. These showed normalization of TRV in 8 patients. Risk factors associated with persistent elevation were higher TRV on initial echocardiogram (P = 0.01), lower haemoglobin (P = 0.003) and lower oxygen saturation (P = 0.03). Five patients with persistently elevated PAP were treated with hydroxyurea. Mean right ventricular pressure dropped from 40.16 to 29.26 (P = 0.017) after 3-6 months and to 23.6 mmHg (P = 0.002) after 9-12 months on treatment. In conclusion (i) At borderline elevation of TRV there is intrapatient variability and echocardiograms should be repeated for confirmation. (ii) Elevated PAP are reversible in children with early detection and treatment with hydroxyurea.

Pulmonary arterial hypertension in children: a medical update

PURPOSE OF REVIEW

With rapid advances in the understanding and treatment of pulmonary arterial hypertension, navigating the pediatric literature becomes challenging. A comprehensive review of the most recent literature over the past year on available and emerging novel therapies as well as an approach to target pediatric populations will provide insight into the current management of pediatric pulmonary hypertension patients.

RECENT FINDINGS

Recent therapeutic advances have significantly improved the prognosis for children with pulmonary arterial hypertension. Pediatric pulmonary arterial hypertension continues to be a serious condition, however, which is extremely challenging to manage. There are also new target groups, such as those with sickle cell disease, congenital diaphragmatic hernia and Eisenmenger syndrome who may be candidates for treatments previously used for idiopathic pulmonary arterial hypertension patients.

SUMMARY

The data in children are often limited to case reports as many of those described here. Thus, the reader needs to be cautious about the interpretation of such small uncontrolled studies. While many of these data support the rationale for using novel agents for children with pulmonary arterial hypertension, further controlled and well designed studies are necessary to assess the true impact of these agents on various subgroups of children with pulmonary arterial hypertension.

Pulmonary hypertension associated with sickle cell disease: pathophysiology and rationale for treatment

Approximately one third of patients with sickle cell disease (SCD) have pulmonary hypertension (PH), which increases their risk of death. Endothelin (ET)-1 is elevated in SCD and appears to play a key role in many of the pathologic processes in this disease, including PH, suggesting that endothelin receptor antagonists such as bosentan may be effective in treating patients with SCD, particularly those with PH. Other possible treatments include sildenafil, epoprostenol, and oral arginine. Data from controlled clinical trials are needed to establish the most effective treatment of patients with PH associated with SCD.

Prevalence and risk factors of elevated pulmonary artery pressures in children with sickle cell disease

OBJECTIVES

The objectives of this study were (1) to determine the prevalence and risk factors of elevated pulmonary artery pressures in children with homozygous SS or Sbeta(0) thalassemia using Doppler echocardiography and (2) to determine a correlation between abnormal transcranial Doppler examinations and elevated pulmonary artery pressures.

METHODS

Screening echocardiograms were prospectively performed during an annual comprehensive clinic visit on children who were older than 6 years and had homozygous SS or Sbeta(0) thalassemia. Detailed history, examination, and laboratory tests were done, and transcranial Doppler examinations were obtained in children 2 to 14 years of age. Pulmonary hypertension was defined as pulmonary artery systolic pressure of at least 30 mmHg corresponding to a peak tricuspid regurgitant jet velocity of > or = 2.5 m/second. Mild pulmonary hypertension was defined as tricuspid regurgitant jet velocity > or = 2.5 to 2.9 m/second. Moderate pulmonary hypertension was defined as tricuspid regurgitant jet velocity > or = 3 m/second. Patients with pulmonary stenosis or right outflow obstruction were excluded. Characteristics were compared between patients with mild, moderate, and no pulmonary hypertension using 1-way analysis of variance for continuous variable and Fisher's exact test for categorical variables.

RESULTS

Of the 75 patients who had homozygous SS/Sbeta(0) thalassemia and were older than 6 years, echocardiograms were obtained for 62 (82.6%). Thirty percent (19 of 62) of patients had elevated tricuspid regurgitant jet velocity > or = 2.5 m/second. One third of these patients had tricuspid regurgitant jet velocity > or = 3 m/second. All patients with elevated tricuspid regurgitant jet velocity had SS disease. A high reticulocyte count, low oxygen saturation, and a high platelet count were significantly associated with elevated pulmonary artery pressures. There was no difference in age, gender, history of acute chest syndrome, hydroxyurea therapy, chronic blood transfusion, stroke, hemoglobin, and bilirubin between patients with and without elevated pulmonary artery pressures. A total of 47% patients with elevated tricuspid regurgitant jet velocity and 57% without elevated tricuspid regurgitant jet velocity had screening transcranial Doppler examinations. Transcranial Doppler examinations were normal for all patients.

CONCLUSIONS

High pulmonary artery pressures do occur in children with sickle cell disease. Screening by echocardiography can lead to early detection and intervention that may potentially reverse this disease process. There was no correlation between elevated pulmonary artery pressures and abnormal transcranial Doppler examination in our study.

Pulmonary hypertension in children and adolescents with sickle cell disease

The prevalence of pulmonary hypertension (PHTN) in the pediatric sickle cell disease (SCD) population is not known despite its high prevalence in adult patients. Our hypothesis was that increased pulmonary artery pressures (PAPs) would be found in SCD children and adolescents, especially those with a history of pulmonary complications: acute chest syndrome, obstructive sleep apnea, asthma, and reactive airway disease. Fifty-two SCD children, 23 of whom had underlying pulmonary disease, were screened for PHTN, which was defined as a tricuspid regurgitant jet velocity (TRV) of at least 2.5 m/s. Twenty-four (46.15%) SCD patients had increased PAP (i.e., TRV > or =2.5 m/s), and 6 (11.5%) had significant PHTN (i.e., TRV > or =3.0 m/s). Pulmonary disease was marginally associated with PHTN (odds ratio 2.80 and confidence interval 0.88 to 8.86; p = 0.0795). As in adult SCD patients with PHTN, this complication was correlated with the degree of hemolysis as manifested by significantly higher lactate dehydrogenase and bilirubin, lower hemoglobin and hematocrit levels, and a strong association with Hb-SS phenotype. However, after statistical adjustment for age and sex, increased serum LDH was not associated with the development of PHTN. Further studies are needed to clarify the prevalence and mechanisms of PHTN in pediatric and adolescent patients with SCD.

Clinical differences between children and adults with pulmonary hypertension and sickle cell disease

Pulmonary hypertension (PHT) is an important co-morbidity in sickle cell disease (SCD). Despite increasing research in adults, the prevalence and implication of this condition in children is unknown. Charts of 362 SCD patients followed at the Children's Hospital & Research Center Oakland were reviewed to determine clinical variables associated with obtaining echocardiographic screening for PHT, clinical associations of PHT, and associated mortality following diagnosis in adults and children with SCD. In this cohort, patients with underlying lung abnormalities or those on chronic transfusions were more likely to have echocardiograms, however the diagnosis of PHT was often unrecognized. A different clinical phenotype for PHT in adults versus children was identified. Associations with PHT for adults included age, renal and lung disease, hepatitis C, chronic transfusions, and a history of acute chest syndrome (ACS), with ACS being protective. Surprisingly, for children, a history of sepsis, along with a history of ACS, or obstructive lung disease were associated with PHT. Survival analysis found significant mortality for PHT, with a hazard ratio of 17.3 (95% confidence interval 4.9-60.4). The divergent clinical spectrum for PHT between adults and children may point to different age-specific mechanisms or biological expression of PHT.

High prevalence of pulmonary hypertension in children with sickle cell disease

Pulmonary hypertension (PHT) affects approximately 30% of adults with sickle cell disease. Adults with PHT have a significantly higher mortality rate. We report the results of a prospective study of the prevalence of PHT among children with sickle cell disease. In our cohort, 31% of children>or=10 years of age have evidence of PHT by Doppler echocardiography. Factors associated with the presence of PHT are male sex and elevated reticulocyte count. We recommend screening all children for PHT starting at the age of 10 years.

Matched-related donor transplantation for sickle cell disease: report from the Center for International Blood and Transplant Research

We report outcomes after myeloablative haematopoietic cell transplantation (HCT) from human leucocyte antigen (HLA)-matched sibling donors in 67 patients with sickle cell disease transplanted between 1989 and 2002. The most common indications for transplantation were stroke and recurrent vaso-occlusive crisis in 38% and 37% of patients respectively. The median age at transplantation was 10 years and 67% of patients had received >10 red blood cell transfusions before HCT. Twenty-seven percent of patients had a poor performance score at transplantation. Ninety-four percent received busulfan and cyclophosphamide-containing conditioning regimens and bone marrow was the predominant source of donor cells. Most patients achieved haematopoietic recovery and no deaths occurred during the early post-transplant period. Rates of acute and chronic graft-versus-host disease were 10% and 22% respectively. Sixty-four of 67 patients are alive with 5-year probabilities of disease-free and overall survival of 85% and 97% respectively. Nine patients had graft failure with recovery of sickle erythropoiesis, eight of who had recurrent sickle-related events. This report confirms and extends earlier reports that HCT from HLA-matched related donors offers a very high survival rate, with few transplant-related complications and the elimination of sickle-related complications in the majority of patients who undergo this therapy.

Antibiotics for treating acute chest syndrome in people with sickle cell disease

BACKGROUND

The clinical presentation of acute chest syndrome is similar whether due to infectious or non-infectious causes, thus antibiotics are usually prescribed to treat all episodes. Many different bacteria have been implicated as causative agents of acute chest syndrome. There is no standardized approach to antibiotic therapy and treatment is likely to vary from country to country. Thus, there is a need to identify the efficacy and safety of different antibiotic treatment approaches for people with sickle cell disease suffering from acute chest syndrome.

OBJECTIVES

To determine whether an empirical antibiotic treatment approach (used either alone or in combination): (a) is effective in treating acute chest syndrome compared to placebo or standard treatment; (b) is safe in treating acute chest syndrome compared to placebo or standard treatment; (c) differs dependent on the regimen used in treating acute chest syndrome differ from each other with respect to efficacy and safety; and (d) varies between different age groups, regions or countries with respect to efficacy and safety.

SEARCH STRATEGY

We searched The Group's Haemoglobinopathies Trials Register, which comprises references identified from comprehensive electronic database searches and handsearching of relevant journals and abstract books of conference proceedings. We also searched the LILACS database (1982 to May 2006) and the website: http://www.clinicaltrials.gov (May 2006). Date of most recent search of the Haemoglobinopathies Trials Register: February 2007.

SELECTION CRITERIA

We searched for published or unpublished randomised controlled trials.

DATA COLLECTION AND ANALYSIS

Each author intended to independently extract data and assess trial quality by standard Cochrane Collaboration methodologies, but no eligible randomized controlled trials were identified.

MAIN RESULTS

We were unable to find any randomised controlled trials on antibiotic treatment approaches for acute chest syndrome in people with sickle cell disease.

AUTHORS' CONCLUSIONS

We were unable to identify randomised controlled trials on efficacy and safety of the antibiotic treatment approaches for people with sickle cell disease suffering from acute chest syndrome. Randomised controlled trials are needed to establish the optimum antibiotic treatment for this condition.

Pulmonary hypertension in sickle cell disease: relevance to children

Pulmonary arterial hypertension (PAH), once considered a rare complication of sickle cell disease (SCD) and thalassemia, appears to be more common in adults with hemoglobinopathy than previously appreciated. On prospective screening of adults with SCD, approximately one-third of adults are found on echocardiography to have a tricuspid regurgitant jet velocity (TRV) of 2.5 m/s or higher, many of whom are asymptomatic. Dyspnea on exertion is the most common presenting symptom. This TRV abnormality is a marker for approximately 40% 3-year mortality in adults, and it is associated with laboratory values suggestive of more severe intravascular hemolysis. Release of hemoglobin and arginase from lysed red cells causes scavenging of nitric oxide (NO) and catabolism of L-arginine, the obligate substrate for NO synthase. The resulting impairment in NO bioavailability is associated with pulmonary vasoconstriction, endothelial dysfunction, thrombosis, and eventual development of plexogenic arterial lesions, the histological hallmark of all forms of PAH. Undoubtedly, additional pathophysiological mechanisms will also play a role in its multifactorial pathogenesis. Early data from children with SCD indicate a similar prevalence of elevated TRV, but the prognostic implications of this remain to be established. Individual patient diagnosis of PAH requires confirmation by right heart catheterization studies and individualized management. Hemolysis-associated PAH with impairments in NO bioavailability is being identified in thalassemia and other hemolytic disorders, and may be a general consequence of long-standing, severe intravascular hemolytic anemia.

Clinical hemoglobinopathies: iron, lungs and new blood

PURPOSE OF REVIEW

Sickle cell disease and beta-thalassemia major are clinically significant hereditary anemias that elicit worldwide attention due to the frequency and severity of these disorders. Historically, most children who inherited these disorders died in the first decade of life. Recently, however, supportive care has extended lifespan through the fifth decade of life and beyond, with survival through early adulthood now indistinguishable from those unaffected by these disorders. As a result, chronic health impairments that significantly reduce the quality of life such as pulmonary hypertension and the consequences of transfusional iron overload have become principal challenges.

RECENT FINDINGS

We focus on important recent advances that are very likely to alter the nature of supportive care of these disorders or make it possible to identify prospectively high-risk patients who might benefit from novel therapies or even curative treatment in the form of hematopoietic cell transplantation. The availability of the latter, traditionally constrained by the requirement of a human leukocyte antigen-identical sibling donor, is very likely to be broadened as results after unrelated donor hematopoietic cell transplantation improve.

SUMMARY

In this review, several areas that are very likely to have a significant impact in the management of patients who inherit these disorders are discussed.