Ventricular diastolic dysfunction in sickle cell anemia is common but not associated with myocardial iron deposition

Altered ventricular longitudinal strain in children with sickle cell disease: Role of TGF-β and IL-18

BACKGROUND

Cardiovascular involvement in sickle cell disease (SCD) has a great impact on patients' morbidity and mortality. Recently, interleukin-18 (IL-18) and transforming growth factor beta (TGF-β) were suggested as potential biomarkers for sickle cell cardiomyopathy. Global longitudinal strain (GLS) is a reliable early parameter for estimation of deformed myocardium. This study evaluated the role of TGF-β and IL-18 as risk indicators of altered strain in patients with SCD.

METHODS

Forty children with SCD (age >5 years) and 40 healthy children as controls, matched in age and sex, were enrolled in the study. All participants were subjected to clinical examination, complete blood count, serum ferritin, TGF-β, IL-18, and assessment of cardiac function by echocardiography.

RESULTS

TGF-β, IL-18, and lactic acid dehydrogenase (LDH) were significantly higher among cases (mean age: 10.6 ± 3.5 years) when compared to controls (p < .001), at cutoff values 41.7 ng/mL, 128.9 pg/mL, and 340 unit, respectively. The LS of free wall of RV (FW-RV) was significantly lower among cases when compared to controls (-23.55% ± 5.55% vs. -28.73% ± 2.43%, p < .001). Free wall longitudinal strain of the right ventricle (FWLS-RV) was significantly correlated to IL-18 and LDH (p < .001), while GLS-RV was significantly correlated to TGF-β. The GLS-LV was correlated to frequency of vaso-occlusive crises (VOCs) per year (p < .001). Diastolic function, E/A of LV, and RV were negatively correlated to the hemoglobin and serum ferritin levels.

CONCLUSIONS

The TGF-β, IL-18, and LDH along with frequent VOCs are correlated to altered LS, especially the right ventricle, and could serve as risk indicators for subclinical cardiomyopathy in children with SCD.

Rapid MRI Assessment of Long-Axis Strain to Indicate Systolic Dysfunction in Patients With Sickle Cell Disease

BACKGROUND

Patients with sickle cell disease (SCD) have a unique form of cardiomyopathy. However, left ventricular ejection fraction (LVEF) is often preserved. Monoplanar long-axis strain (LAS) can be assessed from MRI four-chamber views and may be better at detecting mild systolic dysfunction in these patients.

PURPOSE

To compare LAS (monoplanar and biplanar) with LVEF as a marker of systolic dysfunction in SCD patients.

STUDY TYPE

Retrospective.

SUBJECTS

A total of 20 patients with genetically proven SCD (35 MRI examinations), 39 healthy controls, and 124 patients with systemic iron overload (for validation purposes).

FIELD STRENGTH/SEQUENCE

1.5 T/3 T. Cine balanced steady-state free-precession.

ASSESSMENT

Rapidly assessed biplanar LAS from four- and two-chamber views was correlated with age and compared to LVEF by two operators. For validation, biplanar LAS was compared to global longitudinal strain (GLS) using MRI feature-tracking in 124 patients with systemic iron overload.

STATISTICAL TESTS

Bland-Altman analysis. Wilcoxon-Mann-Whitney test and Spearman-rank correlation (correlation coefficient, rS ). Receiver-operating-characteristic (ROC) curve analysis (area under the curve, AUC). Bivariate discriminant analysis. Significance level: P < 0.01.

RESULTS

There was strong correlation between biplanar LAS and GLS using feature tracking (rS  = 0.73). Interoperator agreement showed nonsignificant bias for biplanar LAS (-0.02%; ±95%-agreement interval -2.2%/2.2%, P = 0.9). Biplanar LAS increased significantly with age in controls (rS  = 0.70). In SCD patients, biplanar LAS was better correlated with age than monoplanar LAS (r2  = 0.53, standard error of estimate, SEE = 1.4% vs. r2  = 0.37;SEE = 2.0%). ROC analysis of LVEF, biplanar LAS, and age-adjusted Z-scores Z (LAS(age)) showed AUCs of 0.69, 0.75, and 0.86 for differentiation between SCD patients and controls. Bivariate discriminant analysis of biplanar Z (LAS(age)) and LVEF revealed a sensitivity of 63% and a specificity of 95%.

DATA CONCLUSION

Rapidly assessed biplanar LAS demonstrated high diagnostic accuracy and was an indicator of mild systolic dysfunction in patients with SCD. Biplanar LAS provided more precise measurements than monoplanar, and normalization to age increased diagnostic accuracy.

EVIDENCE LEVEL

3.

TECHNICAL EFFICACY

Stage 2.

Longitudinal effect of disease-modifying therapy on left ventricular diastolic function in children with sickle cell anemia

Cardiac abnormalities seen in sickle cell anemia (SCA) include diastolic dysfunction, which has been shown to be associated with high morbidity and early mortality. The effect of disease-modifying therapies (DMT) on diastolic dysfunction is poorly understood. We prospectively evaluated the effects of hydroxyurea and monthly erythrocyte transfusions on diastolic function parameters over 2 years. A total of 204 subjects with HbSS or HbSβ0-thalassemia (mean age 11 ± 3.7 years), unselected for disease severity, had diastolic function assessed with surveillance echocardiograms twice, 2 years apart. During this 2-year observation period, 112 participants received DMTs (hydroxyurea, n = 72, monthly erythrocyte transfusions, n = 40), 34 initiated hydroxyurea, and 58 did not receive any DMT. The entire cohort showed an increase in left atrial volume index (LAVi) of 3.40 ± 10.86 mL/m2, p = .001 over 2 years. This increase in LAVi was independently associated with anemia, high baseline E/e' or LV dilation. Individuals not exposed to DMT were younger (mean age 8.8 ± 2.9 years), but at baseline their prevalence of abnormal diastolic parameters was similar to that of the DMT-exposed participants who were older (mean age 12 ± 3.8 years). Participants on DMTs saw no improvement in diastolic function over the study period. In fact, participants on hydroxyurea saw a possible worsening in diastolic parameters (14% increase in LAVi and ~5% decrease in septal e') but also a ~9% decrease in fetal hemoglobin (HbF) levels. Further studies are needed to evaluate if exposure to DMT for a longer duration or achieving higher HbF might be beneficial in alleviating diastolic dysfunction.

Cardiovascular consequences of sickle cell disease

Sickle cell disease (SCD) is an inherited blood disorder caused by a single point mutation within the beta globin gene. As a result of this mutation, hemoglobin polymerizes under low oxygen conditions causing red blood cells to deform, become more adhesive, and increase in rigidity, which affects blood flow dynamics. This process leads to enhanced red blood cell interactions with the endothelium and contributes to vaso-occlusion formation. Although traditionally defined as a red blood cell disorder, individuals with SCD are affected by numerous clinical consequences including stroke, painful crisis episodes, bone infarctions, and several organ-specific complications. Elevated cardiac output, endothelium activation along with the sickling process, and the vaso-occlusion events pose strains on the cardiovascular system. We will present a review of the cardiovascular consequences of sickle cell disease and show connections with the vasculopathy related to SCD. We will also highlight biophysical properties and engineering tools that have been used to characterize the disease. Finally, we will discuss therapies for SCD and potential implications on SCD cardiomyopathy.

Serum or plasma ferritin concentration as an index of iron deficiency and overload

BACKGROUND

Reference standard indices of iron deficiency and iron overload are generally invasive, expensive, and can be unpleasant or occasionally risky. Ferritin is an iron storage protein and its concentration in the plasma or serum reflects iron stores; low ferritin indicates iron deficiency, while elevated ferritin reflects risk of iron overload. However, ferritin is also an acute-phase protein and its levels are elevated in inflammation and infection. The use of ferritin as a diagnostic test of iron deficiency and overload is a common clinical practice.

OBJECTIVES

To determine the diagnostic accuracy of ferritin concentrations (serum or plasma) for detecting iron deficiency and risk of iron overload in primary and secondary iron-loading syndromes.

SEARCH METHODS

We searched the following databases (10 June 2020): DARE (Cochrane Library) Issue 2 of 4 2015, HTA (Cochrane Library) Issue 4 of 4 2016, CENTRAL (Cochrane Library) Issue 6 of 12 2020, MEDLINE (OVID) 1946 to 9 June 2020, Embase (OVID) 1947 to week 23 2020, CINAHL (Ebsco) 1982 to June 2020, Web of Science (ISI) SCI, SSCI, CPCI-exp & CPCI-SSH to June 2020, POPLINE 16/8/18, Open Grey (10/6/20), TRoPHI (10/6/20), Bibliomap (10/6/20), IBECS (10/6/20), SCIELO (10/6/20), Global Index Medicus (10/6/20) AIM, IMSEAR, WPRIM, IMEMR, LILACS (10/6/20), PAHO (10/6/20), WHOLIS 10/6/20, IndMED (16/8/18) and Native Health Research Database (10/6/20). We also searched two trials registers and contacted relevant organisations for unpublished studies.

SELECTION CRITERIA

We included all study designs seeking to evaluate serum or plasma ferritin concentrations measured by any current or previously available quantitative assay as an index of iron status in individuals of any age, sex, clinical and physiological status from any country.

DATA COLLECTION AND ANALYSIS

We followed standard Cochrane methods. We designed the data extraction form to record results for ferritin concentration as the index test, and bone marrow iron content for iron deficiency and liver iron content for iron overload as the reference standards. Two other authors further extracted and validated the number of true positive, true negative, false positive, false negative cases, and extracted or derived the sensitivity, specificity, positive and negative predictive values for each threshold presented for iron deficiency and iron overload in included studies. We assessed risk of bias and applicability using the Quality Assessment of Diagnostic Accuracy Studies (QUADAS)-2 tool. We used GRADE assessment to enable the quality of evidence and hence strength of evidence for our conclusions.

MAIN RESULTS

Our search was conducted initially in 2014 and updated in 2017, 2018 and 2020 (10 June). We identified 21,217 records and screened 14,244 records after duplicates were removed. We assessed 316 records in full text. We excluded 190 studies (193 records) with reasons and included 108 studies (111 records) in the qualitative and quantitative analysis. There were 11 studies (12 records) that we screened from the last search update and appeared eligible for a future analysis. We decided to enter these as awaiting classification. We stratified the analysis first by participant clinical status: apparently healthy and non-healthy populations. We then stratified by age and pregnancy status as: infants and children, adolescents, pregnant women, and adults. Iron deficiency We included 72 studies (75 records) involving 6059 participants. Apparently healthy populations Five studies screened for iron deficiency in people without apparent illness. In the general adult population, three studies reported sensitivities of 63% to 100% at the optimum cutoff for ferritin, with corresponding specificities of 92% to 98%, but the ferritin cutoffs varied between studies. One study in healthy children reported a sensitivity of 74% and a specificity of 77%. One study in pregnant women reported a sensitivity of 88% and a specificity of 100%. Overall confidence in these estimates was very low because of potential bias, indirectness, and sparse and heterogenous evidence. No studies screened for iron overload in apparently healthy people. People presenting for medical care There were 63 studies among adults presenting for medical care (5042 participants). For a sample of 1000 subjects with a 35% prevalence of iron deficiency (of the included studies in this category) and supposing a 85% specificity, there would be 315 iron-deficient subjects correctly classified as having iron deficiency and 35 iron-deficient subjects incorrectly classified as not having iron deficiency, leading to a 90% sensitivity. Thresholds proposed by the authors of the included studies ranged between 12 to 200 µg/L. The estimated diagnostic odds ratio was 50. Among non-healthy adults using a fixed threshold of 30 μg/L (nine studies, 512 participants, low-certainty evidence), the pooled estimate for sensitivity was 79% with a 95% confidence interval of (58%, 91%) and specificity of 98%, with a 95% confidence interval of (91%, 100%). The estimated diagnostic odds ratio was 140, a relatively highly informative test. Iron overload We included 36 studies (36 records) involving 1927 participants. All studies concerned non-healthy populations. There were no studies targeting either infants, children, or pregnant women. Among all populations (one threshold for males and females; 36 studies, 1927 participants, very low-certainty evidence): for a sample of 1000 subjects with a 42% prevalence of iron overload (of the included studies in this category) and supposing a 65% specificity, there would be 332 iron-overloaded subjects correctly classified as having iron overload and 85 iron-overloaded subjects incorrectly classified as not having iron overload, leading to a 80% sensitivity. The estimated diagnostic odds ratio was 8.

AUTHORS' CONCLUSIONS

At a threshold of 30 micrograms/L, there is low-certainty evidence that blood ferritin concentration is reasonably sensitive and a very specific test for iron deficiency in people presenting for medical care. There is very low certainty that high concentrations of ferritin provide a sensitive test for iron overload in people where this condition is suspected. There is insufficient evidence to know whether ferritin concentration performs similarly when screening asymptomatic people for iron deficiency or overload.

Association of Anemia and Blood Pressure With Novel Markers of Diastolic Function in Pediatric Sickle Cell Disease

Diastolic dysfunction is a known cause of mortality in adults with sickle cell disease (SCD). Left atrial function (LAf) and strain (LAS) are novel echocardiographic parameters to assess early diastolic dysfunction, which have not been assessed in pediatric SCD. Through a retrospective single-center study, we describe echocardiographic parameters of diastology in children with SCD and evaluate their relationship with clinical variables including anemia and blood pressure. Baseline clinical data, 24-hour ambulatory blood pressure monitoring data and echocardiography results were collected. LAf and LAS were measured using volumetric data and speckle-tracking echocardiography, respectively. Sixty-seven children with SCD (13.5±7 y, 47% male, 7% hypertensive) with a mean hemoglobin of 8.8±1.3 g/dL, LAf of 61±8% (n=53) and LAS of 46.3±7.4% (n=28) were included. LAS was significantly associated with hemoglobin (ρ=0.43, P=0.022) but not with maximal left atrial (LA) volume (ρ=-0.05, P=0.79) or any blood pressure parameters. On multivariate analysis, LAS decreased by 3.2% (1.3, 5.1) and LA volume increased by 1.6 mL/m2 (3.1, 0.08) for every 1 g/dL decrease in hemoglobin. Thus, severity of baseline anemia in pediatric SCD correlates with diastolic function as measured by LAS, independent of LA dilation.

Discrepancy in patterns of myocardial involvement in beta-thalassaemia vs. sickle cell anaemia

Introduction: Different mechanisms contribute to myocardial dysfunction in sickle cell disease [SCD] and beta thalassaemia major [TM]. TM mainly involves the highly vascular subepicardium by iron load and SCD mainly operates by inducing ischaemia in the relatively ischaemic subendocardium. The aim of this article was to determine if pattern of left ventricular [LV] dysfunction differ among the two groups of patients.Methods: Forty TM and 40 SCD patients and 40 age- and surface area-matched controls were subjected to conventional echocardiography, 2D Speckle tracking myocardial layer strain discriminating echocardiography (MLSD-STE) which is able to discriminate if myocardial dysfunction is predominantly subepicardial or subendocardial and 3D echocardiography for ejection fraction assessment as well as haemoglobin, ferritin, and lactate dehydrogenase levels.Results: TM patients had a deeper subepicardial dysfunction while SCD had prevalent subendocardial dysfunction, epicardial GLS (TM: -10.9 ± 2 vs. SCD: 19.9 ± 1.7; p value < 0.01); endocardial GLS (TM: -19.9 ± 1.7 vs. SCD: -10.6 ± 1.6, p value < 0.01).Conclusion: This study points towards divergent microcirculatory mechanisms in the pathogenesis of myocardial dysfunction in haemoglobinopathies. It shows predominant subendocardial dysfunction with underlying ischaemia of SCD and prevalent subepicardial iron-induced injury in cases of TM.

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.

Tilt-table Echocardiography Unmasks Early Diastolic Dysfunction in Patients With Hemoglobinopathies

Individuals with hemoglobinopathy (sickle cell anemia and thalassemia major) are at risk for cardiac complications such as heart failure and cardiomyopathy. Diastolic dysfunction is known to precede systolic dysfunction in many cardiac diseases. This study sought to determine whether changes in left atrial (LA) function during manipulation of cardiac preload by tilt-table echocardiography can unmask subclinical diastolic dysfunction in pediatric patients with hemoglobinopathies. Eleven sickle cell anemia, 9 transfusion-dependent thalassemia major, and 10 control subjects underwent tilt-table echocardiogram in the supine (loading) and 30-degree upright (unloading) positions and cardiac magnetic resonance imaging (MRI). Echocardiography assessed LA and left ventricular (LV) strain, strain rate, mitral inflow, and annular velocities. MRI assessed LV function, myocardial T1 and T2* for iron deposition. Both thalassemia major and sickle cell anemia patients had normal LV function and no evidence of cardiac iron deposition on MRI T2* measurements. During cardiac loading, controls appropriately increased LA conduit (P=0.002) and reservoir strain (P=0.002), mitral e' velocity (P<0.0001) and medial e' velocity (P=0.002), while the hemoglobinopathy patients showed no change in these parameters. In pediatric sickle cell anemia and thalassemia, tilt-table echocardiography unmasked a failure to augment LA function in response to loading, suggesting altered myocardial relaxation is present, before evidence of iron overload or systolic dysfunction.

Evaluation of Cardiac Function in Patients with Sickle Cell Disease with Left Ventricular Global Longitudinal Strain

Background and Objectives

The importance of myocardial dysfunction in sickle cell disease (SCD) is currently debated. It is difficult to find a reliable index of function in patients with chronic overload as in SCD. Speckle tracking echocardiography, a new mean of evaluating cardiac function, might be a useful tool in SCD. It has been applied in many fields to detect early cardiac function deterioration, and it is less load dependent compared with other function parameters. Studies in patients with SCD are rare, and the results are conflicting. The present study aimed to determine whether left ventricular global longitudinal strain (LV-GLS) was abnormal in a population of adults with SCD and whether it was correlated with clinical or biological parameters.

Methods

We prospectively enrolled 37 patients and 34 age- and sex-matched healthy controls. Echocardiography was performed in patients and controls.

Results

We found that the left ventricular diameter and mass were higher and the ejection fraction and longitudinal strain were lower in patients compared with controls. Diastolic dysfunction was uncommon. LV-GLS was abnormal in 21% of the patients. No correlation was observed between strain and clinical or biological parameters.

Conclusions

We concluded that LV-GLS could be a useful tool for evaluating these patients. However, the clinical impact of reduced LV-GLS remains to be determined.

Right ventricular function among South East Nigeria children with sickle cell anaemia

BACKGROUND

Sickle cell anaemia (SCA) is characterized by attendant ischemia-reperfusion injury especially to the heart.

METHODS

The aim of this work is to compare the right ventricular function of children with SCA in steady state (subjects) with those with haemoglobin AA genotype (controls), using echocardiography. It is a cross-sectional study, which echocardiographic measurements to assess right ventricular function among children with SCA and their controls.

RESULTS

The mean trans annular plane systolic excursion (TAPSE) in subjects, 28.24 ± 5.23 (Z score: 0.258 ± 1.10) was higher than that in control, 25.82 ± 3.59 (Z score: - 0.263 ± 0.80), and the difference in mean was statistically significant, (t = 2.703, p = 0.008). Significantly higher proportion of subjects with sickle cell anaemia had right ventricular dysfunction (Abnormal TAPSE), 25 (50.0%) when compared with those in control, 11 (22.0%), {χ2 = 8.5, p = 0.0035}. A higher proportion of subjects with sickle cell anaemia (25.5%) had Pulmonary hypertension (RVP) when compared with control (2.0%) and the difference in proportions was found to be statistically significant, (χ2 = 11.668, p = 0.001). The prevalence of right ventricular diastolic dysfunction in subjects was 9.8% while control was 0%.

CONCLUSION

Children with sickle cell anaemia present with right ventricular dysfunction. Prevalence of right ventricular systolic and diastolic dysfunction were higher in subjects. More of the subjects in this study (25.5%) had pulmonary hypertension.

Life-Threatening Infectious Complications in Sickle Cell Disease: A Concise Narrative Review

Sickle cell disease (SCD) results in chronic hemolytic anemia, recurrent vascular occlusion, insidious vital organ deterioration, early mortality, and diminished quality of life. Life-threatening acute physiologic crises may occur on a background of progressive diminishing vital organ function. Sickle hemoglobin polymerizes in the deoxygenated state, resulting in erythrocyte membrane deformation, vascular occlusion, and hemolysis. Vascular occlusion and increased blood viscosity results in functional asplenia and immune deficiency in early childhood, resulting in life-long increased susceptibility to serious bacterial infections. Infection remains a main cause of overall mortality in patients with SCD in low- and middle-income countries due to increased exposure to pathogens, increased co-morbidities such as malnutrition, lower vaccination rates, and diminished access to definitive care, including antibiotics and blood. Thus, the greatest gains in preventing infection-associated mortality can be achieved by addressing these factors for SCD patients in austere environments. In contrast, in high-income countries, perinatal diagnosis of SCD, antimicrobial prophylaxis, vaccination, aggressive use of antibiotics for febrile episodes, and the availability of contemporary critical care resources have resulted in a significant reduction in deaths from infection; however, chronic organ injury is problematic. All clinicians, regardless of their discipline, who assume the care of SCD patients must understand the importance of infectious disease as a contributor to death and disability. In this concise narrative review, we summarize the data that describes the importance of infectious diseases as a contributor to death and disability in SCD and discuss pathophysiology, prevalent organisms, prevention, management of acute episodes of critical illness, and ongoing care.

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.

Myocardial Iron Overload in Sickle Cell Disease: A Rare But Potentially Fatal Complication of Transfusion

Sickle cell disease (SCD) is a frequent indication for chronic transfusion, which can cause iron overload. Excess iron often affects the liver, but not the heart in SCD. Magnetic resonance (MR) is recommended to detect myocardial iron overload (MIO) but its elevated cost requires optimized indication. We aimed to compile all published data on MIO in SCD upon the description of a fatal case of severe MIO in our institution, and to determine associated risk factors. We performed a systematic review using the PRISMA guidelines in two databases (PubMed and Web of Science). Inclusion criteria were publication in English, patients diagnosed with SCD, and reporting ferritin and MIO by MR. Twenty publications reported on 865 SCD adult and pediatric patients, with at least 10 other cases of MIO. The prevalence of MIO in chronically transfused SCD patients can be estimated to be 3% or less, and is associated with high transfusion burden, top-up transfusions, and low adherence to iron chelation. Cardiac siderosis in SCD is rarely reported, and increased awareness with better use of the available screening tools are necessary. Prospective studies should define the recommended chelation regimens depending on the severity of MIO.

Sickle Cell Disease: Monitoring, Current Treatment, and Therapeutics Under Development

Screening and early detection of organ injury, as well as expanded use of red cell transfusion and hydroxyurea in children have changed best practices for clinical care in sickle cell disease. The current standard of care for children with sickle cell disease is discussed through a review of screening recommendations, disease monitoring, and approach to treatment. Novel pharmacologic agents under investigation in clinical trials are also reviewed.

Vascular complications of sickle cell disease

Sickle cell disease (SCD) is a monogenetic disorder caused by a mutation in the β-globin gene HBB leading to polymerization of red blood cells causing damage to cell membranes, increasing its rigidity and intravascular hemolysis. Multiple lines of evidence suggest that SCD can be viewed as pan-vasculopathy associated with multiple mechanisms but driven by hemoglobin S polymerization. Here we review the pathophysiology, clinical manifestations and management strategies for cerebrovascular disease, pulmonary hypertension and renal disease associated with SCD. These "vascular phenotypes" reflect the systemic nature of the complications of SCD and are a major threat to the well-being of patients with the disorder.

Left ventricular structural and functional changes evaluated by echocardiography and two-dimensional strain in patients with sickle cell disease

INTRODUCTION

Patients with sickle cell disease have increased left ventricular size, which is not usually accompanied by changes in systolic function indexes. We assessed echocardiographic abnormalities present in patients with sickle cell anemia (SCA) and compared echocardiographic parameters to other sickle cell diseases (OSCD).

MATERIAL AND METHODS

A blind cross-sectional study with 60 patients with SCA and 16 patients with OSCD who underwent transthoracic echocardiography was performed.

RESULTS

Echocardiographic findings were: left atrial volume index 47.7 ±11.5 ml/m² in SCA group and 31.7 ±8.42 ml/m² in OSCD group (p < 0.001); left ventricular diastolic diameter index 3.47 ±0.37 cm/m² in SCA group and 2.97 ±0.41 cm/m² in OSCD group (p < 0.001); left ventricular systolic diameter index 2.12 ±0.31 cm/m² in SCA group and 1.86 ±0.28 cm/m² in OSCD group (p < 0.001). There were no differences in the left ventricular ejection fraction: 68.2 ±6.69% in SCA group and 67.1 ±6.21% in OSCD group (p = 0.527). The ratio between mitral E wave and mean mitral annulus e' wave velocities was higher in the SCA group (7.72 ±1.54 vs. 6.70 ±1.65; p = 0.047). Mitral A wave correlated significantly with hemoglobin levels (r = -0.340; p = 0.032).

CONCLUSIONS

There was an increase of left ventricular and left atrial sizes in patients with SCA, compared to patients with OSCD, without changes in systolic or diastolic function in both groups. This could be due to the hyperkinetic state due to the more severe anemia in the SCA subjects.

Overnight auto-adjusting continuous airway pressure + standard care compared with standard care alone in the prevention of morbidity in sickle cell disease phase II (POMS2b): study protocol for a randomised controlled trial

Background

In addition to pain, sickle cell anaemia (HbSS) complications include neurocognitive difficulties in attention and processing speed associated with low daytime and night-time oxygen saturation compounded by obstructive sleep apnoea (OSA). In the general population OSA is treated with continuous positive airways pressure (CPAP). The aim of this single-blind, randomised, controlled phase II trial is to compare auto-adjusting CPAP (APAP) with standard care to standard care alone in individuals with HbSS to determine whether the intervention improves attention and processing speed, brain structure, pain and quality of life.

Methods/Design

Eligibility criteria include: ability to provide informed consent; age > 8 years; diagnosis of HbSS; and mean overnight saturation of < 90% for < 30% of the night (i.e. not meeting current criteria for overnight oxygen therapy). Key exclusion criteria are: overnight respiratory support; respiratory or decompensated cardiac failure; chronic transfusion; or contraindications to APAP therapy or magnetic resonance imaging (MRI).

Sixty individuals with HbSS (30 children and 30 adults) will be randomised to standard care + APAP or standard care alone for six months. Minimisation factors are: age group (8–11, 12–15, 16–22 and > 23 years); silent infarction on MRI; minimum overnight oxygen saturation > 90% or < 90%; and hydroxyurea use.

For APAP individuals, the intervention is administered at home. Adherence and effectiveness are recorded using software documenting hours of use each night and overnight oximetry. Participant support in terms of appropriate facemask and facilitating adherence are provided by an unblinded sleep physiologist.

The primary outcome is change in the cancellation subtest from the Wechsler scales. Secondary outcomes include general cognitive functioning, quantitative brain MRI, blood and urine chemistry, quality of life and daily pain via a smartphone App (GoMedSolutions, Inc) and, where possible MRI heart, echocardiography, and 6-min walk. These outcomes will be assessed at baseline and after six months of treatment by assessors blind to treatment assignment.

Discussion

Altering oxygen saturation in HbSS may lead to bone marrow suppression. This risk will be reduced by monitoring full blood counts at baseline, two weeks, three months and six months, providing treatment as appropriate and reporting as safety events.

Trial registration

ISRCTN46012373. Registered on 10 July 2015.

Protocol Version: 6.0 Date: 24th December 2015

Sponsor: University Hospital Southampton. Sponsor’s protocol code: RHMCHIOT53

A reappraisal of the mechanisms underlying the cardiac complications of sickle cell anemia

Anemia, hemolysis-driven vasculopathy, and intrinsic myocardial injury have been proposed as predisposing factors to cardiac disease in sickle cell anemia (SCA). The individual impact of these mechanisms on the cardiac features of SCA and the way they influence complications such as sudden death and dysrhythmias have been unclear. Recent findings of an acquired restrictive SCA-related cardiomyopathy, driven by myocardial fibrosis, may explain some of these cardiac features. Given the complexity of cardiac pathology in SCA, using additional parameters to tricuspid regurgitant jet velocity (left atrial volume, diastolic parameters, NT-proBNP) may improve the accuracy of noninvasive screening for cardiopulmonary complications in SCA.

Applications of cardiac magnetic resonance imaging in sickle cell disease

Cardiac magnetic resonance imaging (CMR) has evolved from an effective research tool to a non-invasive clinical modality with versatile applications. The accuracy of volume measurements and functional assessment and the ability to identify unique myocardial tissue characteristics non-invasively are the primary advantages of CMR. The use of CMR in sickle cell disease (SCD) has been limited clinically to myocardial iron assessment. The use of other CMR applications to characterize the cardiac pathology in SCD is slowly emerging but remains limited to research level. In this review, we discuss some of the applications of CMR in studying cardiovascular diseases and its potential uses in SCD for research and clinical purposes.

Impact of sickle cell anaemia on cardiac chamber size in the paediatric population

Purpose Sickle cell disease is known to cause various degrees of vasculopathy, including impact on heart function. The aims of this single-centre, retrospective study were to assess cardiac chamber size and function and the relationship with haematological indices such as haemoglobin, aspartate aminotransferase, reticulocytosis and bilirubin, lactate dehydrogenase in sickle cell disease.

METHODS

Right ventricle and left ventricle diastolic diameters, left ventricle mass estimate, left ventricle shortening fraction, myocardial performance index, and an index of myocardial relaxation (E/E') were calculated and correlated with haematological parameters.

RESULTS

A total of 110 patients (65% haemoglobin SS, 29% haemoglobin SC) were studied at a mean age of 12.14±5.26 years. Right ventricle dilatation and left ventricle dilatation were present in 61.5 and 42.9%, respectively. Left ventricle mass was abnormal in 21.9%; all patients had normal myocardial performance index, 31.4% had abnormal E/E', and left ventricle shortening fraction was low in 38.1%. Cardiac dilatation was best correlated with haemoglobin, aspartate aminotransferase, reticulocytosis and bilirubin. Best subset regression analysis yielded significant additional prediction for right ventricle or left ventricle dilatation with haemoglobin, bilirubin, and lactate dehydrogenase. Abnormal E/E' was solely predictable with haemoglobin level. Hydroxyurea-treated patients had improved diastolic function.

CONCLUSION

Right ventricle dilatation was more prevalent than left ventricle dilatation. The long-term consequences of right ventricular dilatation, clinical consequences, and association with pulmonary vasculopathy need to be further determined.

Speckle tracking evaluation of right ventricular functions in children with sickle cell disease

Background:

Cardiac dysfunction is a risk factor for death in patients with sickle cell disease (SCD).

Aim of the Work:

Aim of the work is to evaluate the right ventricular systolic and diastolic functions by tissue Doppler and speckling tracking imaging in children with SCD.

Subjects and Methods:

Thirty children with SCD and thirty controls were subjected to clinical, laboratory evaluations, and echocardiographic study using GE Vivid 7 (GE Medical System, Horten, Norway with a 3.5-MHz multifrequency transducer) including; Two-dimensional and tissue Doppler echocardiographic study (lateral tricuspid valve annulus peak E’ velocity, lateral tricuspid valve annulus peak A’ velocity, E’/A’ ratio, isovolumetric relaxation time, lateral tricuspid valve annulus S’ and septal S’ waves and peak longitudinal systolic strain [PLSS] and time to PLSS) were done in six right ventricular segments.

Results:

There was a significant decrease in right ventricular systolic and diastolic function in patients group when compared to controls.

Conclusions:

Children with SCD have impaired right ventricular systolic and diastolic functions when compared to healthy children with early evaluation of the systolic dysfunction by speckle tracking imaging technique.

Hormonal and echocardiographic abnormalities in adult patients with sickle-cell anemia in Bahrain

BACKGROUND

Adrenal, thyroid, and parathyroid gland hormonal changes are recognized in children with homozygous (HbSS) sickle-cell anemia (SCA), but are not clear in adult patients with SCA.

AIM

To assess the metabolic and endocrine abnormalities in adult patients with SCA and evaluate left ventricular (LV) systolic and diastolic functions compared with patients with no SCA and further study the relationship between serum levels of cortisol, free thyroxine (T4), and testosterone with serum ferritin.

MATERIALS AND METHODS

The study was conducted on 82 patients with adult HbSS SCA compared with a sex- and age-matched control group. The serum levels of cortisol, parathyroid hormone (PTH), testosterone, thyroid-stimulating hormone (TSH), and free T4 were compared. Blood levels of hemoglobin, reticulocyte count, lactate dehydrogenase (LDH), calcium, alkaline phosphatase (ALP), vitamin D₃, and ferritin were also compared. Pulsed Doppler echo was performed to evaluate the LV mass, wall thickness, and cavity dimensions with diastolic filling velocities of early (E) and atria (A) waves. Biometric data were analyzed as mean ± standard deviation between the two groups. Multiple regression analysis was performed between serum levels of ferritin as independent variable and testosterone, cortisol, and thyroid hormones.

RESULTS

A total of 82 adult patients with HbSS SCA were enrolled who had a mean age of 21±5.7 years, with 51 males (62%). Patients with SCA compared with the control group had significantly lower hemoglobin, body mass index, cortisol, vitamin D₃, testosterone, and T4. Furthermore, there were significantly high levels of reticulocyte count, PTH, TSH, ferritin, LDH, ALP, and uric acid. The incidence of subclinical hypothyroidism and adrenal insufficiency was 7% and 4.8%, respectively, with hypogonadism 9.8% and vitamin D₃ deficiency 61%. There were inverse relationships between ferritin as independent variable and serum levels of testosterone, T4, and cortisol, with regression coefficients of -0.49 (P<0.001), -0.33 (P<0.001), and -0.11 (P<0.92), respectively.

CONCLUSION

Patients with adult SCA had a high prevalence of in vivo hypoadrenialism (4.8%), hypogonadism (9.8%), and hypothyroidism (7%). There were significant inverse relationships between serum ferritin as independent variable and cortisol, testosterone, and T4. Pulsed Doppler echocardiography showed increased LV mass, with a restrictive LV diastolic pattern suggestive of diastolic dysfunction.

Sickle cell anemia mice develop a unique cardiomyopathy with restrictive physiology

Cardiopulmonary complications are the leading cause of mortality in sickle cell anemia (SCA). Elevated tricuspid regurgitant jet velocity, pulmonary hypertension, diastolic, and autonomic dysfunction have all been described, but a unifying pathophysiology and mechanism explaining the poor prognosis and propensity to sudden death has been elusive. Herein, SCA mice underwent a longitudinal comprehensive cardiac analysis, combining state-of-the-art cardiac imaging with electrocardiography, histopathology, and molecular analysis to determine the basis of cardiac dysfunction. We show that in SCA mice, anemia-induced hyperdynamic physiology was gradually superimposed with restrictive physiology, characterized by progressive left atrial enlargement and diastolic dysfunction with preserved systolic function. This phenomenon was absent in WT mice with experimentally induced chronic anemia of similar degree and duration. Restrictive physiology was associated with microscopic cardiomyocyte loss and secondary fibrosis detectable as increased extracellular volume by cardiac-MRI. Ultrastructural mitochondrial changes were consistent with severe chronic hypoxia/ischemia and sarcomere diastolic-length was shortened. Transcriptome analysis revealed up-regulation of genes involving angiogenesis, extracellular-matrix, circadian-rhythm, oxidative stress, and hypoxia, whereas ion-channel transport and cardiac conduction were down-regulated. Indeed, progressive corrected QT prolongation, arrhythmias, and ischemic changes were noted in SCA mice before sudden death. Sudden cardiac death is common in humans with restrictive cardiomyopathies and long QT syndromes. Our findings may thus provide a unifying cardiac pathophysiology that explains the reported cardiac abnormalities and sudden death seen in humans with SCA.

Cardiovascular complications and risk of death in sickle-cell disease

In sickle-cell disease, a point mutation in the β-globin chain causes haemoglobin to polymerise within erythrocytes during deoxygenation, altering red blood cell rheology and causing haemolysis. Improvements in health infrastructure, preventive care, and clinical treatments have reduced the morbidity and mortality of sickle-cell disease in developed countries. However, as these patients live longer, the chronic effects of sustained haemolytic anaemia and episodic vaso-occlusive events drive the development of end-organ complications. Cardiopulmonary organ dysfunction and chronic kidney injury have a large effect on morbidity and premature mortality, and typically accelerate in the second decade of life. These processes culminate in the development of pulmonary hypertension, left ventricular diastolic heart disease, dysrhythmia, and sudden death. In this Series paper, we review the mechanisms, clinical features, and epidemiology of major cardiovascular complications in patients with sickle-cell disease and discuss how screening and intervention could reduce their incidence.

Tissue Doppler Imaging-derived Diastolic Function Assessment in Children With Sickle Cell Disease and Its Relation With Ferritin

Diastolic dysfunction has been shown to occur earlier than systolic dysfunction in iron overload states in adult patients with sickle cell disease (SCD). Tissue Doppler imaging (TDI)-derived E/E' has emerged as a noninvasive marker of diastolic function. We sought to determine diastolic function in children with SCD and study its relation with iron overload. A retrospective review of medical records of 225 pediatric patients with SCD who received an echocardiogram between January 2008 and December 2012 was performed. Echocardiographic measures including M-mode, spectral Doppler, and TDI-derived E/E' were compared with previously published data in healthy children. The left ventricular end-diastolic and end-systolic dimensions were significantly higher in SCD (P<0.0001) and the shortening fraction was similar (P=0.66). E/E' ratio was significantly higher in SCD at the mitral annulus, septum, and tricuspid annulus. In 54% of subjects, the septal E/E' was >8, indicating elevated left ventricular filling pressure. However, there was no significant correlation between ferritin level and E/E' ratios. Pediatric patients with SCD have a high prevalence of elevated estimated left ventricular filling pressure, but this does not correlate with ferritin levels.

Assessment of cardiac functions in children with sickle cell anemia: doppler tissue imaging study

BACKGROUND AND AIMS

The extent in which sickle cell anemia (SCA) impacts myocardial function in children is unclear. Doppler tissue imaging (DTI) was introduced as a new non-invasive echocardiographic method for assessment of ventricular systolic and diastolic functions. We undertook this study to assess subclinical impact of SCA on global myocardial performance in affected children using DTI and to correlate it with mean hemoglobin concentration.

METHODS

Eighty five children with SCA (mean age 11.82 ± 3.7 years) was included as the study group and 55 age- and sex-matched healthy children as the control group. Conventional two-dimensional echocardiography was performed in both groups and DTI was used to determine right ventricular (RV) and left ventricular (LV) Tei indexes. Mean Hb concentration was correlated to the cardiac functions of SCA children.

RESULTS

RV and LV Tei indexes were significantly higher in SCA group (mean ± SD: 0.54 ± 0.19 vs. 0.27 ± 0.01, p <0.0001 and 0.47 ± 0.09 vs. 0.30 ± 0.07, p <0.0001, respectively). Also, mean Hb concentration was correlated negatively with both LV Tei index (r = -0.611, p <0.0001) and with RV Tei index (r = -0.894, p <0.0001). On the contrary, fractional shortening (FS) did not correlate with mean Hb concentration (r = -0.044, p = 0.681).

CONCLUSIONS

DTI technique appears to be more sensitive than conventional echocardiography in the early detection of myocardial dysfunction in children with SCA. This provides insights into the value of early screening and the potential for preventive therapy in children to avert cardiac morbidity and mortality in adults with SCA.

Left ventricular remodeling in patients with sickle cell disease: determinants factors and impact on outcome

Cardiovascular complications have been increasingly detected as a result of prolonged longevity of patients with sickle cell disease (SCD). Previous studies have focused especially on pulmonary hypertension and its consequences on the right-side heart chambers, whereas factors associated with morphological changes in left ventricle (LV) remain poorly understood. This study was designed to identify clinical, laboratorial, and echocardiographic parameters associated with LV remodeling and its impact on outcome in SCD. Ninety patients aged 28 ± 7 years and 20 age- and gender-balanced healthy subjects were enrolled. Laboratory tests, electrocardiogram, and an echocardiogram with tissue Doppler imaging were performed in all patients. Patients with SCD had larger left and right heart chambers dimensions, LV mass, and tricuspid regurgitation (TR) velocity compared to health controls with similar demographic features. Despite chambers enlargement, systolic function of both ventricles was preserved. The mitral inflow velocities were higher in the patients than in controls, whereas septal and lateral annular motion velocities were normal, suggesting normal ventricular relaxation. SCD patients who were on hydroxyurea therapy and/or hypertransfusion had higher hemoglobin concentrations, but similar echocardiographic findings in comparison to those without treatment. Systolic blood pressure, ferritin concentration, TR velocity, and parameters of diastolic function were independently associated with increased LV mass. In addition, the predictors of adverse events were ferritin concentration, lactate dehydrogenase levels, and TR velocity. LV remodeling in SCD patients seems to be influenced by a combination of factors including blood pressure, ferritin concentration, TR velocity, and parameters of LV diastolic function, and was not associated with adverse outcomes.

Left ventricular rotational mechanics in Tanzanian children with sickle cell disease

Background

Sickle cell disease (SCD) is a common inherited hemoglobinopathy. Adults with SCD manifest both systolic and diastolic cardiac dysfunction, though the age of onset of dysfunction has not been defined. Left ventricular (LV) rotational mechanics have not been studied in children with SCD. The aim of this study was to investigate whether cardiac rotational mechanics differed between children with SCD and age-matched controls.

Methods

Basal and apical LV short-axis images were acquired prospectively in 213 patients with SCD (mean age, 14.1 ± 2.6 years) and 49 controls (mean age, 13.3 ± 2.8 years) from the Muhimbili Sickle Cohort in Dar es Salaam, Tanzania. The magnitude of basal and apical rotation, net twist angle, torsion, and untwist rate were obtained by two-dimensional speckle-tracking. The timing of events was normalized to aortic valve closure.

Results

Mean basal rotation was significantly lower in patients with SCD compared with controls (P = .012), although no difference was observed in apical rotation (P = .37). No statistically significant differences in torsion or net twist angle were detected. Rotation rate at the apex (P = .001) and base (P = .0004) were significantly slower in subjects with SCD compared with controls. Mean peak untwisting rate was also significantly slower in patients with SCD (P = .006). No associations were found between hemoglobin concentration and apical rotation, basal rotation, net twist, and torsion.

Conclusion

This study demonstrates alterations in LV rotational mechanics in children with SCD, including lower basal rotation, peak differential twist, and untwist rate. These abnormalities denote subclinical changes in LV systolic and diastolic performance in children with SCD. Future work may reveal an association between rotational metrics and long-term patient outcomes.

The current state of imaging pediatric hemoglobinopathies

The hemoglobinopathies are a group of genetic disorders with a broad spectrum of clinical manifestations and radiologic findings. The imaging of pediatric hemoglobinopathies, which is influenced by concomitant hemosiderosis and the sequela of chelation therapy, has evolved over the years along with ever-improving technology. This article reviews and illustrates the most common radiographic and cross-sectional imaging findings of the 2 best known and clinically relevant hemoglobinopathies in pediatric patients, sickle cell disease and β-thalassemia.

Iron deficiency anemia in infants: does it really affect the myocardial functions?

The aim was to assess the myocardial functions in infants with iron deficiency anemia (IDA). The findings of 22 infants with IDA and 16 healthy infants were compared. Complete blood count in all infants, serum iron level, total iron binding capacity (TIBC), and serum ferritin level in patients were evaluated. Echocardiography with tissue Doppler imaging (TDI) was performed in all infants. The mean hemoglobin was 8.5 versus 11 g/dL, hematocrit was 26.7 versus 33.1% and the mean corpuscular volume (MCV) was 59.8 versus 72.2 fL in patients and controls, respectively. The median serum iron level was 14.5 μg/dL, TIBC was 444 μg/dL, and serum ferritin level was 4.9 ng/mL in patients. There were significant differences between patients and controls for the myocardial performance indexes of the left ventricle (LV) (0.57 vs. 0.45, P < .05), interventricular septum (IVS) (0.56 vs. 0.48, P < .05), and the right ventricle (RV) (0.56 vs. 0.41, P < .05). The similar significances were also present for the ejection times (ET) of the LV (173.1 vs. 212.1 ms, P < .05), IVS (173.7 vs. 195.6 ms, P < .05), and RV (169.9 vs. 213.3 ms, P < .05). In spite of negatively significant correlations between hemoglobin, hematocrit, MCV and MPI, the correlations between these parameters and ET were positively significant. However, there were no correlations between serum iron level, TIBC, serum ferritin level, and the TDI parameters of patients. According to these findings, we could say that, the IDA affects the myocardial functions in a negative manner.

Left ventricular dyssynchrony is an early manifestation of heart involvement in sickle cell anemia

BACKGROUND

Sickle cell anemia (SCA) is the most common inherited anemia. Although heart involvement in SCA is well-established, there is no data about changes of contraction synchrony in SCA. Therefore, we aimed to study the left ventricular contraction synchrony in SCA patients with narrow QRS and normal ejection fraction (EF).

METHODS

Thirty-six patients with SCA and 37 age- and gender-matched control subjects were included in the study. Left ventricular dyssynchrony was investigated by color-coded tissue Doppler imaging.

RESULTS

The SCA patients had lower hemoglobin (Hb) and higher ferritin, left ventricular end-diastolic diameter, left ventricular end-systolic diameter, left ventricular mass index (LVMI), and pulmonary artery pressure. Peak A velocity, Dt, and E/E' values were higher in the SCA group however, E/A ratio and average Em were higher in the control group. LV systolic dyssynchrony parameters including Ts-SD-12, Ts-12, Ts-SD-6, and Ts-6 were found to be higher in SCA group when compared with controls. In addition to that, the patients with ventricular dyssynchrony (a Ts-SD-12 > 34.4 msec) were higher in the SCA group than the control group (55.6% vs. 8.1%, P < 0.001). In the correlation analysis, systolic dyssynchrony parameters were found to be correlated with Hb, ferritin, LVMI, E/A, Dt, Em.

CONCLUSION

Our results revealed that in SCA patients with normal EF and narrow QRS, left ventricular systolic dyssynchrony was an early manifestation of heart involvement and might be coexisted with or preceding diastolic dysfunction.

Cardiovascular abnormalities in sickle cell disease

Sickle cell disease is characterized by recurrent episodes of ischemia-reperfusion injury to multiple vital organ systems and a chronic hemolytic anemia, both contributing to progressive organ dysfunction. The introduction of treatments that induce protective fetal hemoglobin and reduce infectious complications has greatly prolonged survival. However, with increased longevity, cardiovascular complications are increasingly evident, with the notable development of a progressive proliferative systemic vasculopathy, pulmonary hypertension (PH), and left ventricular diastolic dysfunction. Pulmonary hypertension is reported in autopsy studies, and numerous clinical studies have shown that increased pulmonary pressures are an important risk marker for mortality in these patients. In epidemiological studies, the development of PH is associated with intravascular hemolysis, cutaneous leg ulceration, renal insufficiency, iron overload, and liver dysfunction. Chronic anemia in sickle cell disease results in cardiac chamber dilation and a compensatory increase in left ventricular mass. This is often accompanied by left ventricular diastolic dysfunction that has also been a strong independent predictor of mortality in patients with sickle cell disease. Both PH and diastolic dysfunction are associated with marked abnormalities in exercise capacity in these patients. Sudden death is an increasingly recognized problem, and further cardiac investigations are necessary to recognize and treat high-risk patients.

Evaluation of myocardial deformation in patients with sickle cell disease and preserved ejection fraction using three-dimensional speckle tracking echocardiography

BACKGROUND

Sickle cell disease (SCD) is a hemoglobinopathy that affects one in 500 African Americans. Although it is well established that patients with SCD have left ventricular (LV) diastolic dysfunction, it is not clear whether they have subtle LV systolic dysfunction despite preserved ejection fraction (EF). We used three-dimensional speckle tracking echocardiography (3DSTE) to assess changes in both systolic and diastolic LV function in SCD.

METHODS

Transthoracic real time 3D images were obtained (Philips iE33) in 56 subjects, including 28 stable outpatients with SCD (age 33 ± 7 years) and 28 normal controls (age 35 ± 9 years). 3DSTE was performed using prototype software (4DLV Analysis, TomTec) to obtain LV volume and deformation time curves, from which indices of systolic and diastolic LV function were calculated.

RESULTS

In SCD patients, 3DSTE-derived LV filling parameters were significantly different from normal controls, reflecting an increase in both rapid and atrial filling volumes and prolonged active relaxation, depicted by a decrease in filling volume fractions at fixed times and an increase in rapid filling duration. Global LV systolic function was not only preserved but increased compared to controls, as reflected by significantly increased global longitudinal strain. Importantly, twist angle and torsion as well as radial and circumferential components of 3D strain were similar in both groups.

CONCLUSIONS

3DSTE was able to confirm diastolic dysfunction, as expected in some patients with SCD. However, 3DSTE strain analysis did not reveal any changes in LV systolic function. These findings provide novel insight into the pathophysiology of the cardiovascular complications of SCD.

Ventricular structure and function in children with sickle cell disease using conventional and tissue Doppler echocardiography

Conventional 2-dimensional, M-mode, and spectral Doppler echocardiographic techniques have documented abnormal ventricular function in adults with sickle cell disease (SCD), but assessments in children are conflicting. Tissue Doppler echocardiography (TDE) provides additional information about myocardial function. Two-dimensional, M-mode, tricuspid regurgitation jet velocity (TRJV) data, and tissue Doppler echocardiographically derived myocardial velocity measurements of left ventricular (LV) and right ventricular function were taken from children with SCD compared to those of similar healthy historical controls and correlated with clinical characteristics and hemoglobin levels. Compared to 55 controls, 54 children with SCD (mean age 14.2 years, range 6 to 21) had a larger left ventricle, greater LV mass, and higher LV fractional shortening; 30% had increased pulmonary artery pressure (TRJV ≥2.5 m/s). Conventional echocardiographic measurements of LV systolic function and spectral Doppler measurements of LV and right ventricular diastolic function were essentially normal, but TDE indicated that 31% of SCD children had evidence of LV diastolic dysfunction (peak early diastolic velocity of LV inflow Doppler/peak early diastolic velocity at lateral mitral valve annulus >8), a finding that correlated with lower hemoglobin levels. Although decreasing hemoglobin levels in children with SCD correlated with LV hypertrophy, LV dilation, and LV diastolic dysfunction, long-term transfusion or hydroxyurea therapy did not affect these measurements. In conclusion, 1/3 of children with SCD had tissue Doppler echocardiographic evidence of LV diastolic dysfunction, which was correlated with hemoglobin levels. Adding serial assessments of ventricular function with TDE to conventional echocardiography may detect early cardiac changes, especially in children with severe anemia.

Chronically transfused pediatric sickle cell patients are protected from cardiac iron overload

Iron overload is a major toxicity of chronic transfusions. Myocardial iron overload is associated with cardiac dysfunction. Cardiac and liver magnetic resonance imaging (MRI) was performed on 14 chronically transfused sickle cell disease (SCD) and non-sickle cell disease (non-SCD) patients seen at Vanderbilt Children's Hospital from 1 January 2000 to 10 March 2010. Retrospective review was conducted to assess cardiac T2*, liver T2*, ventricular dimensions and function, echocardiogram, length of transfusion, hemoglobin, and ferritin measurements. Ten patients had SCD and 4 had non-SCD, including α-thalassemia, β-thalassemia, and Diamond-Blackfan anemia. Cardiac T2* was normal in all SCD patients (mean 39 ± 12 ms), but abnormal in 3 of 4 non-SCD patients (mean 11.8 ± 2.4 ms). Liver T2* was similar between SCD (mean 6.2 ± 1.6 ms) and non-SCD patients (mean 5.9 ± 1.9 ms), and did not correlate with serum ferritin. Comparing SCD and non-SCD patients with similar transfusion duration, SCD patients had normal cardiac T2* and non-SCD patients had abnormal cardiac T2*. No patients had cardiomyopathy, but ventricular dilatation was common among SCD patients. Chronically transfused pediatric SCD patients are relatively spared of myocardial iron overload, which is unlikely to be due to lower total body iron burden in SCD patients than non-SCD patients.