Left ventricular systolic function in sickle cell anemia: a meta-analysis

Assessment of Biventricular Systolic and Diastolic Function Using Conventional and Strain Echocardiography in Children with Sickle Cell Disease Surviving 1-year After Hematopoietic Stem Cell Transplant

Hematopoietic stem cell transplant (HSCT) is a potentially curative therapy for children with sickle cell disease (SCD). The effects of HSCT on ventricular function are not well characterized in children with SCD. Echocardiograms from children with SCD who underwent HSCT between 2007 and 2017 were retrospectively analyzed before and 1-year after HSCT. Left ventricular (LV) volumes, mass, and ejection fraction were calculated by the 5/6 area*length method. LV end-diastolic and systolic dimensions, septal, and posterior wall thickness, and fractional shortening were measured by M-mode. Mitral and tricuspid inflow Dopplers (E and A waves) as well as mitral, tricuspid, and septal tissue Dopplers (E', A') were assessed. E/A, E'/A' and E/E' ratios were calculated. Biventricular strain imaging was performed using speckle-tracking echocardiography. Peak global systolic longitudinal and circumferential LV strain, and global longitudinal right ventricular strain, as well as early and late diastolic strain rate, were measured on LV apical 4-chamber, LV short-axis mid-papillary, and RV apical views, respectively. Forty-seven children (9.7 ± 5.5 years, 60% male) met inclusion criteria. Pre-HSCT, subjects had mild LV dilation with normal LV systolic function by conventional measure of ejection fraction and fractional shortening. There was a significant reduction in LV volume, mass, and ejection fraction after HSCT, but measurements remained within normal range. LV longitudinal and circumferential strain were normal pre-HSCT and showed no significant change post-HSCT. RV strain decreased after HSCT, but the absolute change was small, and mean values were normal both pre- and post-HSCT. Conventional measures of diastolic function were all normal pre-HSCT. Post-HSCT there was a reduction in select parameters, but all parameters remained within normal range. Early and late diastolic strain rate parameters showed no significant change from pre- to post-HSCT. At one-year after HSCT in children with SCD conventional measures of systolic and diastolic function are within normal limits. Except for a small decrease in RV systolic strain with values remaining within normal limits, systolic strain and diastolic strain rate values did not significantly change 1-year after HSCT.

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.

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

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

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.

Prognostic value of multiparametric cardiac magnetic resonance in sickle cell patients

The aim of this multicenter study was to prospectively assess the predictive value of multiparametric cardiac magnetic resonance (CMR) for cardiovascular complications in sickle cell disease (SCD) patients. Among all patients with hemoglobinopathies consecutively enrolled in the Myocardial Iron Overload in Thalassemia (MIOT) Network, we selected 102 SCD patients (34.38 ± 12.67 years, 49 females). Myocardial iron overload (MIO) was measured by the multislice multiecho T2* technique. Atrial dimensions and biventricular function parameters were quantified by cine images. Late gadolinium enhancement (LGE) images were acquired to detect focal myocardial fibrosis. At baseline CMR, only two patients had significant MIO (global heart T2* < 20 ms). During a mean follow-up of 63.01 ± 24.95 months, 11 cardiovascular events (10.8%) were registered: 3 pulmonary hypertension, 2 supraventricular arrhythmias, 1 heart failure, 1 death for heart failure, 1 pulmonary embolism, 1 peripheral vascular disease, 1 transient ischemic attack, and 1 death after acute chest syndrome. In the multivariate analysis, the independent CMR predictors of cardiovascular events were left ventricular (LV) ejection fraction (hazard ratio-HR = 0.88; p = 0.025) and right ventricular (RV) mass index (HR = 1.09; p = 0.047). According to the receiver-operating characteristic curve analysis for adverse events, an LV ejection fraction < 58.9% and an RV mass index > 31 g/m² were optimal cut-off values. Reduced left ventricular ejection fraction and increased right ventricular mass index showed a significant prognostic value in patients with SCD. Our data seem to suggest that CMR may be added as a screening tool for identifying SCD patients at high risk for cardiopulmonary and vascular diseases.

Pulmonary hypertension due to high cardiac output

Pulmonary hypertension (PH) is usually associated with a normal or decreased cardiac output (CO). Less commonly, PH can occur in the context of a hyperdynamic circulation, characterized by high CO (>8 L/min) and/or cardiac index ≥4 L/min/m² in the setting of a decreased systemic vascular resistance. PH due to high CO can occur due to multiple conditions and in general remains understudied. In this review article we describe the pathophysiology, etiology, diagnosis, hemodynamic characteristics, and management of PH in the setting of high CO. It is important to recognize this distinct entity as PH tends to improve with treatment of the underlying etiology and PH specific therapies may worsen the hemodynamic state.

Echocardiographic Evaluation in Paediatric Sickle Cell Disease Patients: A Pilot Study

Cardiovascular involvement has a great impact on morbidity and mortality in sickle cell disease (SCD). Currently, few studies are available regarding the paediatric setting and, moreover, current guidelines for the echocardiogram screening program in the asymptomatic paediatric population are controversial. We performed a retrospective observational monocentric study on 64 SCD patients (37 male and 27 female, median age 10) at the Bambino Gesù Childrens' Hospital, who had undergone a routine transthoracic echocardiogram. In total, 46 (72%) patients had at least one cardiac abnormality. Left atrial dilatation (LAD) was present in 41 (65%) patients and left ventricular hypertrophy (LVH) was found in 29 (45%) patients. Patients with LAD showed lower median haemoglobin levels (p = 0.009), and a higher absolute reticulocyte count (p = 0.04). LVH was negatively correlated with the median haemoglobin value (p = 0.006) and positively with the reticulocyte count (p = 0.03). Moreover, we found that patients with cardiac anomalies had higher transfusion needs and a lower frequency of pain crises. In our setting, cardiac involvement has a high prevalence in the paediatric cohort and seems to be associated with specific laboratory findings, and with a specific clinical phenotype characterized by complications related to high haemodynamic load.

Evaluation of left ventricular systolic function in children with sickle cell anemia: contribution of 2D strain

BACKGROUND

Children with sickle cell anemia (SCA) are at an increased risk of cardiovascular complications. The aim of this study was to assess the role of speckle tracking echocardiography in detecting subclinical myocardial damage in children with SCA.

METHODS

A cross-sectional case-control study was conducted at the echocardiography laboratory of the military hospital of Tunis between July and December 2018. Thirty patients with SCA were included. A control(C) group including 30 normally developing children was selected and matched to the SCA group by sex and age. We compared between the two groups: conventional echocardiographic parameters including cardiac output, left ventricular ejection fraction (LVEF), thickness and the global longitudinal strain (GLS). The echocardiographic measurements were indexed according to body surface area. The left ventricular (LV) GLS association with clinical characteristics and echocardiographic parameters were also evaluated.

RESULTS

Patients and controls were matched for age and sex: the mean age was (11± 2years) in SCA group versus (12± 1 years) in C group with a sex ratio of (1.31 versus 1.27, respectively). Body surface area was comparable. LV hypertrophy and dilation were revealed in the SCA group, whereas measurements were normal in the C group. No significant differences were observed for cardiac output (p=0.4). LVEF were preserved in both groups. However, two-dimensional (2D) LVGLS was impaired in 46% of SCA group (n=14) with mean value of (-21%±3.07 vs -25%±2.98; p<0.01).In SCA group, impaired LVGLS was significantly associated with LV mass (r = - 0.399, p<0.01), LV tele diastolic diameter(r= -0.419, p<0.01) and left atrial volume (r= - 0.399, p< 0.04). In multivariate analysis, LV mass was the only independent factor.

CONCLUSIONS

In the present study, LVGLS measurement revealed subclinical LV systolic impairment in patients with SCA. Therefore, 2D strain could be beneficial to detect the natural history of LV dysfunction in SCA.

Evaluation of left ventricular systolic function in children with sickle cell anemia: contribution of 2D strain

BACKGROUND

Cardiovascular involvement is not well studied in children with sickle cell disease. The aim of this study was to evaluate the echocardiographic parameters and to investigate speckle tracking echocardiography (STE) interest in detecting subclinical myocardial impairment of children with sickle cell disease.

METHODS

The study was directed in the echocardiographic laboratory in the military hospital of Tunis between July 2018 and December 2018. 30 patients with sickle cell anemia (SCA) and 30 controls were compared. The echocardiographic measurements were indexed according to body surface. Cardiac output, left ventricular ejection fraction, wall thickness, as well as LV 2-D longitudinal systolic strain were assessed.

RESULTS

The SCA Group included 30 patients (11.8 ± 2yrs, sex ratio: 1.31) with homozygous SCA and the C Group included 30 healthy controls (12.7 ± 1,2yrs, sex ratio: 1.27). According to the findings, SCA Group showed significantly larger LV diameter (36.2±2.5mm/m2 vs 29.3±1.3mm/m2, p=0.005). SCA Group also showed lower LV ejection fraction (62%±0.5 vs 65%±5, p=0.001). No significant difference was observed for cardiac output (p=0.4). Otherwise, two-dimensional longitudinal strain of LV was higher in SCA group (-21%±3.07 vs -25%±2.98; p<0.01).

CONCLUSIONS

Our study highlights several cardiac abnormalities in children with SCA, which could represent a marker of disease severity and point out the importance of the cardiologic screening of these patients.

Longitudinal analysis of cardiac abnormalities in pediatric patients with sickle cell anemia and effect of hydroxyurea therapy

Cardiac abnormalities in children and young adults with sickle cell anemia are common.

Timely initiation of treatment with hydroxyurea may lead to reverse cardiac remodeling and improvement in these cardiac abnormalities.

Cardiac abnormalities such as left ventricular hypertrophy, left ventricular dilation, and pulmonary hypertension in sickle cell anemia have been previously described. Hydroxyurea, a disease-modifying therapy for sickle cell anemia, has been used for several decades. Longitudinal assessment of echocardiographic abnormalities in children and young adults with sickle cell anemia receiving hydroxyurea therapy is lacking. The goal of this retrospective study was to determine the prevalence of echocardiographic abnormalities in children and young adults with sickle cell anemia and to examine the effects of hydroxyurea on reverse cardiac remodeling. We reviewed the records of patients with sickle cell anemia who underwent routine cardiac screening at Cohen Children’s Medical Center between 2010 and 2017, followed by retrospective longitudinal analysis of echocardiograms performed on patients receiving treatment with hydroxyurea. Data on a total of 100 patients with sickle cell anemia were analyzed; 60 (60%) were being treated with hydroxyurea. Twenty-five (41.6%) of the patients on hydroxyurea had been treated for <1 year; these patients had a significantly greater prevalence of left ventricular dilation compared with those who had been on treatment for >1 year. Serial echocardiograms of patients receiving hydroxyurea were then analyzed. Left ventricular dilation and hypertrophy improved significantly with hydroxyurea treatment. In addition, the left ventricular volume and mass correlated negatively with duration of treatment with hydroxyurea. Our study provides evidence that prolonged hydroxyurea therapy may lead to reverse cardiac remodeling. Future studies should attempt to follow up this patient cohort for a longer duration.

The different facets of sickle cell disease-related pulmonary hypertension

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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

Cardiac Chamber Quantification by Echocardiography in Adults With Sickle Cell Disease: Need Attention to Eccentric Hypertrophy

Introduction and aim

Sickle cell anemia (SCA) is the most common hemoglobinopathy worldwide, and cardiovascular diseases are the most common causes of death. In these patients, cardiac remodeling begins from childhood and leads to sickle cell cardiomyopathy in the following years. Concentric hypertrophy and eccentric hypertrophy are known to predict early cardiac events. This study aims to reveal the relationship between cardiac remodeling types and survival in patients with SCA and investigate the factors that may affect left ventricular mass.

Materials and methods

A total of 146 patients with SCA were included in the study, and the left ventricular mass index (LVMI) and relative wall thickness (RWT) of the patients were calculated according to echocardiographic measurements, and the patients were categorized into normal, concentric remodeling (CR), concentric hypertrophy (CH), and eccentric hypertrophy (EH) groups.

Results

The median age of the patients is 32 (18-72). In logistic regression analysis, hemoglobin S (HbS) and ferritin levels were independent predictors for LVMI (p = 0.01 and p < 0.001, respectively). It was observed that 56 (38.4%) of the patients had normal left ventricles, 24 (16.4%) had CR, 21 (14.4%) had CH, and 45 (30.8%) had EH. 31 (21.2%) of the patients died. When we look at the survival curves, there was a statistically significant difference between the four groups (log-rank p < 0.001). It was observed that patients with EH were the group with the lowest probability of survival.

Conclusion

Cardiac death is one of the most common causes of death in patients with SCA. Early detection of cardiac disorders and starting treatment may be important in reducing mortality in these patients.

Vasculopathy in Sickle Cell Disease: From Red Blood Cell Sickling to Vascular Dysfunction

Sickle cell disease (SCD) is a hereditary disorder that leads to the production of an abnormal hemoglobin, hemoglobin S (HbS). HbS polymerizes in deoxygenated conditions, which can prompt red blood cell (RBC) sickling and leaves the RBCs more rigid, fragile, and prone to hemolysis. SCD patients suffer from a plethora of complications, ranging from acute complications, such as characteristic, frequent, and debilitating vaso-occlusive episodes to chronic organ damage. While RBC sickling is the primary event at the origin of vaso-occlusive processes, other factors that can further increase RBC transit times in the microcirculation may also be required to precipitate vaso-occlusive processes. The adhesion of RBC and leukocytes to activated endothelium and the formation of heterocellular aggregates, as well as increased blood viscosity, are among the mechanisms involved in slowing the progress of RBCs in deoxygenated vascular areas, favoring RBC sickling and promoting vascular occlusion. Chronic inflammatory processes and oxidative stress, which are perpetuated by hemolytic events and ischemia-reperfusion injury, result in this pan cellular activation and some acute events, such as stroke and acute chest syndrome, as well as chronic end-organ damage. Furthermore, impaired vasodilation and vasomotor hyperresponsiveness in SCD also contribute to vaso-occlusive processes. Treating SCD as a vascular disease in addition to its hematological perspective, the present article looks at the interplay between abnormal RBC physiology/integrity, vascular dysfunction and clinical severity in SCD, and discusses existing therapies and novel drugs in development that may ameliorate vascular complications in the disease. © 2021 American Physiological Society. Compr Physiol 11:1785-1803, 2021.

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.

Cardiovascular complications of sickle cell disease

Sickle cell disease (SCD) is the most common inherited blood disorder in the United States, and a global health problem. Pathological features of the abnormal hemoglobin (HbS) result in 2 hallmarks of the disease - recurrent episodes of acute microvascular occlusion and chronic hemolytic anemia - that inflict continuous and insidious damage to multiple organs. With improved childhood survival, SCD in adults has evolved into a chronic degenerative disease with underlying damage to multiple organs including the heart and lungs. Cardiopulmonary complications, including cardiomyopathy, diastolic dysfunction, pulmonary hypertension (PH), and sudden cardiac death are the most common causes of morbidity and mortality. Awareness of the sickle-related cardiovascular phenotypes is important for screening, early diagnosis, and intervention of cardiac complications in this disorder.

Cardiovascular manifestations of sickle cell disease

Sickle cell disease (SCD) is the most frequent genetic haemoglobinopathy worldwide. Early childhood mortality has dramatically decreased in high-income countries, and most patients now survive beyond the 5th decade. However, in the aging SCD population, the morbidity related to chronic organ damage, especially kidney and heart, has become a major concern. While pulmonary hypertension has attracted most attention, it appears that this condition is frequently linked to left heart failure (HF). Accordingly, SCD-associated cardiomyopathy is emerging as a major cause of reduced quality of life and early mortality in these patients. The diagnosis of this particular phenotype of high-output HF is challenging. Exercise intolerance and dyspnoea in SCD patients are linked to multiple causes including chronic anaemia. Moreover, echocardiographic features are unusual and can be misinterpreted. The classical diagnosis algorithm for HF is generally not suitable in SCD patients, and HF is poorly recognized and mostly diagnosed at a late congestive stage in routine practice. Such patients need to be identified at an earlier stage of myocardial dysfunction via improved phenotyping. This constitutes the first step towards further investigations in SCD needed to improve the prognosis and the quality of life. This article provides an updated review of the recent advances in the pathophysiology and diagnosis, and in addition, perspectives of new therapeutic approaches in SCD-related cardiac manifestations.

Pathophysiology of Sickle Cell Disease

Since the discovery of sickle cell disease (SCD) in 1910, enormous strides have been made in the elucidation of the pathogenesis of its protean complications, which has inspired recent advances in targeted molecular therapies. In SCD, a single amino acid substitution in the β-globin chain leads to polymerization of mutant hemoglobin S, impairing erythrocyte rheology and survival. Clinically, erythrocyte abnormalities in SCD manifest in hemolytic anemia and cycles of microvascular vaso-occlusion leading to end-organ ischemia-reperfusion injury and infarction. Vaso-occlusive events and intravascular hemolysis promote inflammation and redox instability that lead to progressive small- and large-vessel vasculopathy. Based on current evidence, the pathobiology of SCD is considered to be a vicious cycle of four major processes, all the subject of active study and novel therapeutic targeting: ( a) hemoglobin S polymerization, ( b) impaired biorheology and increased adhesion-mediated vaso-occlusion, ( c) hemolysis-mediated endothelial dysfunction, and ( d) concerted activation of sterile inflammation (Toll-like receptor 4- and inflammasome-dependent innate immune pathways). These molecular, cellular, and biophysical processes synergize to promote acute and chronic pain and end-organ injury and failure in SCD. This review provides an exhaustive overview of the current understanding of the molecular pathophysiology of SCD, how this pathophysiology contributes to complications of the central nervous and cardiopulmonary systems, and how this knowledge is being harnessed to develop current and potential therapies.

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.

Changes in Bi-ventricular Function After Hematopoietic Stem Cell Transplant as Assessed by Speckle Tracking Echocardiography

Hematopoietic stem cell transplant (HSCT) is a therapeutic option for patients with sickle cell disease (SCD) and severe acquired aplastic anemia (SAA). HSCT may have beneficial effects on ventricular function in damaged myocardium. We hypothesized improvement in ventricular performance and pulmonary hypertension following HSCT with strain echocardiography in SCD and SAA. Echocardiographic strain and other standard functional data were obtained via retrospective cohort analysis of patients (n = 23) with SCD and SAA who underwent HSCT and were followed at a single center between 2000 and 2014. Left ventricular global longitudinal strain was below normal at baseline, and decreased significantly (from - 16.6 to - 11.1, P = 0.05) from pre-HSCT to the initial post-HSCT echocardiogram at 109 (SD ± 83) days. At 351 (SD ± 115) days, longitudinal strain improved significantly from initial decline (from - 11.1 to - 17.5, P = 0.009) but was comparable to baseline (P = 0.43). Other measurements of bi-ventricular function did not change significantly. Tricuspid regurgitation velocities as surrogates for pulmonary hypertension improved in the subset of patients with baseline elevated values although data points were limited. Abnormal myocardial systolic function was detected at baseline with strain imaging. HSCT was associated with initial worsening longitudinal strain values, followed by improvement to baseline levels by 1 year. Insufficient data exist on whether pulmonary hypertension improves after HSCT.

Utility of Non-Invasive Monitoring of Cardiac Output and Cerebral Oximetry during Pain Management of Children with Sickle Cell Disease in the Pediatric Emergency Department

Pain crisis in children with sickle cell disease (SCD) is typically managed with intravenous fluids and parenteral opioids in the pediatric emergency department. Electrical cardiometry (EC) can be utilized to measure cardiac output (CO) and cardiac index (CI) non-invasively. Near-infrared spectroscopy (NIRS) measuring cerebral (rCO₂) and splanchnic regional (rSO₂) mixed venous oxygenation non-invasively has been utilized for monitoring children with SCD. We studied the value and correlation of NIRS and EC in monitoring hemodynamic status in children with SCD during pain crisis. We monitored EC and NIRS continuously for 2 h after presentation and during management. Forty-five children participated in the study. CO (D = 1.72), CI (D = 1.31), rSO₂ (D = 11.6), and rCO₂ (D = 9.3), all increased over time. CO max and CI max were achieved 1 h after starting resuscitation. rCO₂ max attainment was quicker than rSO₂, as monitored by NIRS. CI max correlated with rCO₂ max (r = −0.350) and rSO₂ max (r = −0.359). In adjustment models, initial CI significantly impacted initial rCO₂ (p = 0.045) and rCO₂ max (p = 0.043), while initial CO impacted rCO₂ max (p = 0.030). Cardiac output monitoring and NIRS monitoring for cerebral and splanchnic oxygenation were feasible and improved the monitoring of therapeutic interventions for children with SCD during pain crisis.

Sleep-disordered breathing in patients with sickle cell disease

Sickle cell disease is one of the most common hereditary hemoglobinopathies worldwide, and its vaso-occlusive and hemolytic crises cause considerable patient morbidity. A growing body of evidence has shown that sleep-disordered breathing, and in particular, obstructive sleep apnea, occurs at high frequency in the sickle cell population, and that there is significant overlap in the underlying pathophysiology of these two conditions. Through a variety of mechanisms including nocturnal hypoxemia and increased oxidative stress, production of pro-inflammatory cytokines, and endothelial dysfunction, sickle cell anemia and sleep-disordered breathing potentiate each other's clinical effects and end-organ complications. Here, we will review the shared pathophysiologic mechanisms of these conditions and discuss their clinical sequelae. We will also examine the results of studies that have been carried out with clinical intervention of nocturnal hypoxemia in patients with sickle cell disease in the attempts to overcome the complications of the disease. Finally, we will propose the areas of investigation that merit further investigations in future in patients with sickle cell disease and sleep-disordered breathing.

Longitudinal Analysis of Echocardiographic Abnormalities in Children With Sickle Cell Disease

BACKGROUND

Cardiac abnormalities have been described in echocardiograms of children with sickle cell disease (SCD). However, longitudinal studies investigating progression of echocardiographic abnormalities across the pediatric age spectrum in SCD are lacking.

METHODS

A retrospective longitudinal analysis of 829 echocardiograms from pediatric patients with SCD at steady-state was performed. Left heart parameters included left ventricular end-systolic, end-diastolic diameters, fractional shortening, and mass. Right ventricular pressure was estimated by tricuspid regurgitation gradient. Tricuspid regurgitation gradient ≥25 mm Hg, a z-score ≥2 for LV parameters and ≤-2 for left ventricular fractional shortening were considered abnormal.

RESULTS

Kaplan-Meier analysis revealed that echocardiographic abnormalities were detected by 5 years of age, and the cumulative incidence progressively increased throughout childhood. Age, male gender, HbSS and Sβ thalassemia genotype, white blood cell count, platelet count, total bilirubin, admissions for pain crises and acute chest syndrome were positively, whereas hemoglobin was negatively associated with cardiac abnormalities.

CONCLUSION

Cardiac abnormalities began early in childhood and progressively increased with age. Our study highlights the high cumulative incidence of cardiac abnormalities in children with SCD, which could represent a marker of disease severity.

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.

Left ventricular systolic function in sickle cell anaemia: an echocardiographic evaluation in adult Nigerian patients

BACKGROUND

Reliable diagnostic measures for the evaluation of left ventricular systolic performance in the setting of altered myocardial loading characteristics in sickle cell anaemia remains unresolved.

OBJECTIVE

The study was designed to assess left ventricular systolic function in adult sickle cell patients using non-invasive endsystolic stress - end-systolic volume index ratio.

METHODS

A descriptive cross sectional comparative study was done using 52 patients recruited at the adult sickle cell anaemia clinic of the University of Nigeria Teaching Hospital Enugu. An equal number of age and sex-matched healthy volunteers served as controls. All the participants had haematocrit estimation, haemoglobin electrophoresis, as well as echocardiographic evaluation.

RESULT

The mean age of the patients and controls were 23.93 ± 5.28 (range 18-42) and 24.17 ± 4.39 (range 19 -42) years respectively, (t = 0.262; p= .794). No significant difference was seen in estimate of fractional shortening, and ejection fraction. The cardiac out-put, cardiac index and velocity of circumferential shortening were all significantly increased in the cases compared with the controls. The end systolic stress - end systolic volume index ratio (ESS/ESVI) was significantly lower in cases than controls. There were strong positive correlation between the ejection phase indices (ejection fraction and fractional shortening) and end systolic stress and ESS/ESVI.

CONCLUSION

The study findings suggest the presence of left ventricular systolic dysfunction in adult sickle cell anaemia. This is best detected using the loading-pressures independent force-length relationship expressed in ESS/ESVI ratio.

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.

Cardiomyopathy With Restrictive Physiology in Sickle Cell Disease

OBJECTIVES

The aim of this study was to identify a unifying cardiac pathophysiology that explains the cardiac pathological features in sickle cell disease (SCD).

BACKGROUND

Cardiopulmonary complications, the leading cause of adult death in SCD, are associated with heart chamber dilation, diastolic dysfunction, elevated tricuspid regurgitant jet velocity (TRV), and pulmonary hypertension. However, no unifying cardiac pathophysiology has been identified to explain these findings.

METHODS

In a 2-part study, we first examined patients with SCD who underwent screening echocardiography during steady state at our institution. We then conducted a meta-analysis of cardiac studies in SCD.

RESULTS

In the 134 patients with SCD studied (median age 11 years), significant enlargement of the left atrial volume was present (z-score 3.1, p = 0.002), shortening fraction was normal (37.6 ± 4.7%), and lateral and septal ratios of mitral velocity to early diastolic velocity of the mitral annulus (E/e') were severely abnormal in 8% and 14% of patients, respectively, indicating impaired diastolic function. Both TRV and lateral E/e' correlated with enlarged left atrial volume in SCD (p = 0.003 and p = 0.006, respectively). Meta-analysis of 68 studies confirmed significant left atrial diameter enlargement in patients with SCD compared with controls, evidence of diastolic dysfunction and enlarged left ventricular end-diastolic dimension with normal shortening fraction. The majority of patients with catheter-confirmed pulmonary hypertension had mild pulmonary venous hypertension consistent with restrictive cardiac physiology.

CONCLUSIONS

Patients with SCD have a unique form of cardiomyopathy with restrictive physiology that is superimposed on hyperdynamic physiology and is characterized by diastolic dysfunction, left atrial dilation, and normal systolic function. This combination results in mild, secondary, pulmonary venous hypertension and elevated TRV. Sudden death is common in other forms of restrictive cardiomyopathy. Our finding of this unique restrictive cardiomyopathy may explain the increased mortality rates and sudden death seen in patients with SCD with mildly elevated TRV.

Left ventricular hypertrophy in children, adolescents and young adults with sickle cell anemia

OBJECTIVE

The aims of this study were to estimate the frequency of left ventricular hypertrophy and to identify variables associated with this condition in under 25-year-old patients with sickle cell anemia.

METHODS

A cross-sectional study was performed of children, adolescents and young adults with sickle cell anemia submitted to a transthoracic Doppler echocardiography. The mass of the left ventricle was determined by the formula of Devereux et al. with correction for height, and the percentile curves of gender and age were applied. Individuals with rheumatic and congenital heart disease were excluded. The patients were divided into two groups according to the presence or absence of left ventricular hypertrophy and compared according to clinical, echocardiographic and laboratory variables.

RESULTS

A total of 37.6% of the patients had left ventricular hypertrophy in this sample. There was no difference between the groups of patients with and without hypertrophy according to pathological history or clinical characteristics, except possibly for the use of hydroxyurea, more often used in the group without left ventricular hypertrophy. Patients with left ventricular hypertrophy presented larger left atria and lower hemoglobin and hematocrit levels, reticulocyte index and a higher albumin:creatinine ratio in urine.

CONCLUSION

Left ventricular hypertrophy was observed in more than one-third of the young patients with sickle cell anemia with this finding being inversely correlated to the hemoglobin and hematocrit levels, and reticulocyte index and directly associated to a higher albumin/creatinine ratio. It is possible that hydroxyurea had had a protective effect on the development of left ventricular hypertrophy.

Hemoglobinopathies and sleep--The road less traveled

Sickle cell disease and thalassemia are common hereditary blood disorders associated with increased systemic inflammation, tissue hypoxia, endothelial dysfunction and end-organ damage, the latter accounting for the substantial morbidity and abbreviated lifespan associated with these conditions. Sleep perturbations in general, and sleep-disordered breathing in particular are also highly prevalent conditions and the mechanisms underlying their widespread end-organ morbidities markedly and intriguingly overlap with the very same pathways implicated in the hemoglobinopathies. However, little attention has been given to date to the potential contributing role of sleep disorders to sickle cell disease manifestations. Here, we comprehensively review the pathophysiological mechanisms and clinical manifestations linking disturbed sleep and hemoglobinopathies, with special emphasis on sickle cell disease. In addition to a broad summary of the available evidence, we identify many of the research gaps that require attention and future investigation, and provide the scientific contextual setting that should enable opportunities to investigate the intertwined pathophysiological mechanisms and clinical outcomes of sleep disorders and hemoglobinopathies.

Subclinical left ventricular systolic impairment in steady state young adult patients with sickle-cell anemia

Chronic volume overload in sickle-cell anemia (SCA) is associated with left ventricular (LV) enlargement and hypertrophy. The effect of the disease on LV systolic function remains debated. The aim of our study was to investigate LV systolic function in SCA patients using 2D speckle-tracking imaging. We compared 30 steady state asymptomatic adult SCA patients (17 women, mean age 24.7 ± 5.1 years) with 30 age and sex-matched healthy subjects (17 women, mean age 25.0 ± 4.9 years). In addition to conventional echocardiographic parameters including LV ejection fraction (LVEF) and LV mass index (LVMi), global longitudinal strain (GLS) and strain rate (GLSR) were measured. GLS (-17.9 ± 2.0 vs. -19.7 ± 2.5 %, p = 0.004) and GLSR (-0.92 ± 0.09 vs. -1.07 ± 0.17 s(-1), p < 0.0001) values were lower in SCA patients while LVEF values (60.1 ± 3.8 vs. 61.7 ± 4.7 %, p = 0.30) were not different. LVMi was increased in SCA patients (100.7 ± 23.5 vs. 72.4 ± 15.2 g/m(2), p = 0.0001) and GLSR was significantly lower in the subgroup of patients with LV hypertrophy (-0.88 ± 0.09 vs. -0.96 ± 0.08 s(-1), p = 0.02). In SCA patients LVMi was correlated to GLS (r = 0.58, p = 0.001) and GLSR (r = 0.45, p = 0.015) pleading in favor of a pathological LV remodeling. Asymptomatic SCA patients exhibited a subclinical alteration of LV systolic function. Myocardial dysfunction appears to be linked to the degree of LV hypertrophy. 2D speckle-tracking imaging might be useful for long-term follow-up and to study the natural course of LV dysfunction in SCA patients.