Endothelial function and arterial stiffness in sickle-thalassemia patients

The role of extracellular vesicles on the occurrence of clinical complications in β-thalassemia

Thalassemia is the most common monogenic disorder of red blood cells (RBCs) caused by defects in the synthesis of globin chains. Thalassemia phenotypes have a wide spectrum of clinical manifestations and vary from severe anemia requiring regular blood transfusions to clinically asymptomatic states. Ineffective erythropoiesis and toxicity caused by iron overload are major factors responsible for various complications in thalassemia patients, especially patients with β-thalassemia major (β-TM). Common complications in patients with thalassemia include iron overload, thrombosis, cardiac morbidity, vascular dysfunction, inflammation, and organ dysfunction. Extracellular vesicles (EVs) are small membrane vesicles released from various cells' plasma membranes due to activation and apoptosis. Based on studies, EVs play a role in various processes, including clot formation, vascular damage, and proinflammatory processes. In recent years, they have also been studied as biomarkers in the diagnosis and prognosis of diseases. Considering the high concentration of EVs in thalassemia and their role in cellular processes, this study reviews the role of EVs in the common complications of patients with β-thalassemia for the first time.

Orbital bone infarction masquerading as preseptal cellulitis in a child with sickle beta-thalassaemia

Although several ophthalmic manifestations of sickle cell disease (SCD) are common, orbital bone infarction is rare. Orbital bones have less bone marrow creating an unlikely place to develop infarction. However, having a patient with SCD presenting with periorbital swelling should warrant imaging to rule out bone infarction. We present a case of a child with sickle beta-thalassaemia who was misdiagnosed with preseptal cellulitis in the right eye. Later upon review of the subtle signs of bone infarction in imaging, she was discovered to have orbital bone infarction.

T2-weighted cardiovascular magnetic resonance and echocardiographic arterial elasticity criteria for monitoring cardiac siderosis in patients with beta-thalassemia major

Background:

Despite the availability of iron chelators, toxicity due to increased iron load is the leading cause of death in thalassemia major patients, especially in Iran. This study was performed to determine the association between cardiovascular magnetic resonance using T2-weighted sequences (CMR T2*) and diagnostic value of echocardiographic arterial elasticity in major beta-thalassemia patients without cardiac symptoms in Isfahan, Iran, in 2019 and 2021.

Materials and Methods:

This cross-sectional study assessed the association between CMR T2*, advanced echocardiographic arterial elasticity criteria, and serum ferritin in 67 patients with major beta-thalassemia patients without cardiac symptoms at Chamran Cardiovascular, Medical, and Research Center in Isfahan, Iran, in 2019–2021. Data analysis was performed among the 67 patients using SPSS, version 24.0 (Statistical Procedures for Social Sciences, Chicago, Illinois, USA). Spearman's rank test was used to assess the correlation between T2*CMR, echocardiographic arterial elasticity criteria, and ferritin. All parameters are presented as mean ± standard deviation. The results were considered statistically significant at P < 0.05.

Results:

There was a positive correlation between CMR T2* and arterial elastance index (P = 0.035, r = 0.258), according to the Spearman test. In addition, CMR T2* was not correlated with the serum ferritin (P = 0.158, r = 0.201).

Conclusion:

Totally, according to the obtained results, it may be concluded that the arterial elastance index from echocardiography and the CMR T2* may be indicators of myocardial iron overload in patients with major beta-thalassemia patients without cardiac symptoms.

Non-Transferrin-Bound Iron in the Spotlight: Novel Mechanistic Insights into the Vasculotoxic and Atherosclerotic Effect of Iron

Significance: While atherosclerosis is an almost inevitable consequence of aging, food preferences, lack of exercise, and other aspects of the lifestyle in many countries, the identification of new risk factors is of increasing importance to tackle a disease, which has become a major health burden for billions of people. Iron has long been suspected to promote the development of atherosclerosis, but data have been conflicting, and the contribution of iron is still debated controversially. Recent Advances: Several experimental and clinical studies have been recently published about this longstanding controversial problem, highlighting the critical need to unravel the complexity behind this topic. Critical Issues: The aim of the current review is to provide an overview of the current knowledge about the proatherosclerotic impact of iron, and discuss the emerging role of non-transferrin-bound iron (NTBI) as driver of vasculotoxicity and atherosclerosis. Finally, I will provide detailed mechanistic insights on the cellular processes and molecular pathways underlying iron-exacerbated atherosclerosis. Overall, this review highlights a complex framework where NTBI acts at multiple levels in atherosclerosis by altering the serum and vascular microenvironment in a proatherogenic and proinflammatory manner, affecting the functionality and survival of vascular cells, promoting foam cell formation and inducing angiogenesis, calcification, and plaque destabilization. Future Directions: The use of additional iron markers (e.g., NTBI) may help adequately predict predisposition to cardiovascular disease. Clinical studies are needed in the aging population to address the atherogenic role of iron fluctuations within physiological limits and the therapeutic value of iron restriction approaches. Antioxid. Redox Signal. 35, 387-414.

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.

Vasculo-toxic and pro-inflammatory action of unbound haemoglobin, haem and iron in transfusion-dependent patients with haemolytic anaemias

Increasing evidence suggests that free haem and iron exert vasculo‐toxic and pro‐inflammatory effects by activating endothelial and immune cells. In the present retrospective study, we compared serum samples from transfusion‐dependent patients with β‐thalassaemia major and intermedia, hereditary spherocytosis and sickle cell disease (SCD). Haemolysis, transfusions and ineffective erythropoiesis contribute to haem and iron overload in haemolytic patients. In all cohorts we observed increased systemic haem and iron levels associated with scavenger depletion and toxic ‘free’ species formation. Endothelial dysfunction, oxidative stress and inflammation markers were significantly increased compared to healthy donors. In multivariable logistic regression analysis, oxidative stress markers remained significantly associated with both haem‐ and iron‐related parameters, while soluble vascular cell adhesion molecule 1 (sVCAM‐1), soluble endothelial selectin (sE‐selectin) and tumour necrosis factor α (TNFα) showed the strongest association with haem‐related parameters and soluble intercellular adhesion molecule 1 (sICAM‐1), sVCAM‐1, interleukin 6 (IL‐6) and vascular endothelial growth factor (VEGF) with iron‐related parameters. While hereditary spherocytosis was associated with the highest IL‐6 and TNFα levels, β‐thalassaemia major showed limited inflammation compared to SCD. The sVCAM1 increase was significantly lower in patients with SCD receiving exchange compared to simple transfusions. The present results support the involvement of free haem/iron species in the pathogenesis of vascular dysfunction and sterile inflammation in haemolytic diseases, irrespective of the underlying haemolytic mechanism, and highlight the potential therapeutic benefit of iron/haem scavenging therapies in these conditions.

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

BACKGROUND

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

OBJECTIVE

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Unmasking hypertension in children and adolescents with sickle/beta-thalassemia

Sickle cell disease (SCD) is associated with increased risk of cardiovascular disease, although blood pressure (BP) levels have been reported to be lower in SCD patients compared to general population. Aims of the present study were to investigate the prevalence of BP phenotypes and levels of arterial stiffness in pediatric patients with SCD and to assess the differences with children at risk for hypertension. We included in the study 16 pediatric SCD (HbS/β-thalassemia, S/β-thal) patients and 16 consecutive children at risk for hypertension referred to our hypertension clinic that served as high-risk controls. All patients underwent ambulatory BP monitoring and measurement of carotid-femoral pulse wave velocity (PWV). S/β-thal patients had lower office systolic BP than the high-risk control group (115.43 ± 10.03 vs 123.37 ± 11.92, P = .05) but presented similar levels of day and night ambulatory BP. Office hypertension was found in 12.5% of the S/β-thal patients and in 43.8% of the high-risk controls (P = .06), while 18.8% of the S/β-thal patients and 25% of the high-risk controls presented hypertension by ambulatory BP levels (P = .21). All of the S/β-thal patients with ambulatory hypertension had night hypertension (one combined night and day hypertension) with office normotension (masked hypertension). S/β-thal patients and high-risk controls presented equal prevalence of masked hypertension (18.8%). Children and adolescents with S/β-thal present similar prevalence of BP phenotypes and levels of PWV with children at risk for hypertension. A significant number of children and adolescents with S/β-thal may have masked nighttime hypertension despite normal office BP levels.

The changing epidemiology of the ageing thalassaemia populations: A position statement of the Thalassaemia International Federation

Therapeutic advances in β-thalassaemia have gradually lead to a significant improvement in prognosis over the past few decades. As a result, patients living in areas where disease-specific programmes offering access to modern therapy are in place experience a new era of prolonged survival that tends to reach that of the normal population. This ageing thalassaemia population, however, faces a new spectrum of comorbidities resulting from increasing age that may jeopardise the advances in prognosis provided by current therapy and thus poses new challenges in diagnosis, monitoring and treatment. In this position paper of the Thalassaemia International Federation, we review the changing epidemiology and clinical spectrum of patients with β-thalassaemia and propose actions to be undertaken in order to address the emerging spectrum of comorbidities resulting from ageing.

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.

A Pilot Optical Coherence Tomography Angiography Study on Superficial and Deep Capillary Plexus Foveal Avascular Zone in Patients With Beta-Thalassemia Major

Purpose

To investigate foveal avascular zone (FAZ) changes in the superficial (SCP) and deep (DCP) capillary plexuses in beta-thalassemia major (BTM) patients, as shown in optical coherence tomography angiography.

Methods

Nonrandomized, comparative case series of 54 eyes of 27 BTM patients and 46 eyes of 23 healthy controls, utilizing an automated FAZ detection algorithm. Measurements included FAZ area and FAZ shape descriptors (convexity, circularity, and contour temperature). Results were compared between the two groups, and correlated to iron load and chelation therapy parameters.

Results

SCP and DCP FAZ area were not significantly different between the control and BTM groups (P = 0.778 and P = 0.408, respectively). The same was true regarding SCP FAZ convexity (P = 0.946), circularity (P = 0.838), and contour temperature (P = 0.907). In contrast, a statistically significant difference was detected between controls and BTM group regarding DCP FAZ convexity (P = 0.013), circularity (P = 0.010), and contour temperature (P = 0.014). Desferrioxamine dosage was strongly correlated to the DCP area (r = 0.650, P = 0.05) and liver magnetic resonance imaging/T2-star to DCP circularity (r = -0.492, P = 0.038). Correlations were also revealed between urine Fe excretion and DCP convexity (r = 0.531, P = 0.019), circularity (r = 0.661, P = 0.002), and contour temperature (r = -0.591, P = 0.008).

Conclusions

Retinal capillary plexuses and especially DCP seem to present unique morphologic changes in BTM patients, not in the FAZ area, but in specific shape descriptors, indicating minor but detectable FAZ changes. These changes correlate well with iron load and chelation therapy parameters. Their clinical importance and pathophysiologic implications remain to be elucidated through further studies.

Ultrasound Detection of Abnormal Cerebrovascular Morphology in a Mouse Model of Sickle Cell Disease Based on Wave Reflection

Sickle cell disease (SCD) is associated with a high risk of stroke, and affected individuals often have focal brain lesions termed silent cerebral infarcts. The mechanisms leading to these types of injuries are at present poorly understood. Our group has recently demonstrated a non-invasive measurement of cerebrovascular impedance and wave reflection in mice using high-frequency ultrasound in the common carotid artery. To better understand the pathophysiology in SCD, we used this approach in combination with micro-computed tomography to investigate changes in cerebrovascular morphology in the Townes mouse model of SCD. Relative to controls, the SCD mice demonstrated the following: (i) increased carotid artery diameter, blood flow and vessel wall thickness; (ii) elevated pulse wave velocity; (iii) increased reflection coefficient; and (iv) an increase in the total number of vessel segments in the brain. This study highlights the potential for wave reflection to aid the non-invasive clinical assessment of vascular pathology in SCD.

Angiopoietin-2 as a Marker of Retinopathy in Children and Adolescents With Sickle Cell Disease: Relation to Subclinical Atherosclerosis

OBJECTIVES

Angiopoietin-2 (Ang-2) is a multifaceted cytokine that functions in both angiogenesis and inflammation. A proangiogenic state has been found in adults with sickle cell disease (SCD), mainly because of elevated Ang-2 levels. We determined Ang-2 level in 40 children and adolescents with SCD compared with 40 healthy controls and assessed its relation to retinopathy as well as carotid intimamedia thickness (CIMT).

METHODS

Hematologic profile, serum ferritin, and serum Ang-2 were measured. CIMT was assessed using high-resolution ultrasound. Fundus examination was performed followed by fundus fluorescein angiography. Optical coherence tomography angiography (OCTA) was used to find small vascular changes not clinically manifested.

RESULTS

Ang-2 levels and CIMT were significantly higher in SCD patients compared with controls. The incidence of nonproliferative retinopathy was 45%. SCD patients with retinopathy were older in age with a history of sickling crisis of >3 attacks per year and had a higher incidence of sickle cell anemia than sickle β-thalassemia. Ang-2 cutoff value 9000 pg/mL could significantly detect the presence of retinopathy among SCD patients with 100% sensitivity and specificity. Serum Ang-2 levels were positively correlated with HbS and CIMT. Logistic regression analysis revealed that Ang-2 and HbS significantly contribute to retinopathy among patients with SCD.

CONCLUSIONS

Elevated Ang-2 highlights the role of angiogenesis in the pathophysiology of SCD and may be considered a promising marker for screening of patients at risk of sickle retinopathy and vascular dysfunction.

Deferiprone increases endothelial nitric oxide synthase phosphorylation and nitric oxide production

Iron chelation can improve endothelial function. However, effect on endothelial function of deferiprone has not been reported. We hypothesized deferiprone could promote nitric oxide (NO) production in endothelial cells. We studied effects of deferiprone on blood nitrite and blood pressure after single oral dose (25 mg/kg) in healthy subjects and hemoglobin E/β-thalassemia patients. Further, effects of deferiprone on NO production and endothelial NO synthase (eNOS) phosphorylation in primary human pulmonary artery endothelial cells (HPAEC) were investigated in vitro. Blood nitrite levels were higher in patients with deferiprone therapy than those without deferiprone (P = 0.023, n = 16 each). Deferiprone increased nitrite in plasma and whole blood of healthy subjects (P = 0.002 and 0.044) and thalassemia patients (P = 0.003 and 0.046) at time 180 min (n = 20 each). Asymptomatic reduction in diastolic blood pressure (P = 0.005) and increase in heart rate (P = 0.009) were observed in healthy subjects, but not in thalassemia patients. In HPAEC, deferiprone increased cellular nitrite and phospho-eNOS (Ser1177) (P = 0.012 and 0.035, n = 6) without alteration in total eNOS protein and mRNA. We conclude that deferiprone can induce NO production by enhancing eNOS phosphorylation in endothelial cells.

Heart Disease in Patients with Haemoglobinopathies

Hereditary hemoglobin disorders, also termed haemoglobinopathies, include mainly beta -thalasszemia and sickle cell disease and represent the most common monogenic disorders in human [...]

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.

Soluble fms-Like Tyrosine Kinase 1 as a Link Between Angiogenesis and Endothelial Dysfunction in Pediatric Patients With β-Thalassemia Intermedia

Endothelial damage has been implicated in the pathogenesis of vascular complications in β-thalassemia intermedia (β-TI). Soluble fms-like tyrosine kinase 1 (sFLT-1) is a member of the vascular endothelial growth factor receptor (VEGFR) family. Soluble fms-like tyrosine kinase 1 is an antiangiogenic protein that induces endothelial dysfunction by adhering to and inhibiting VEGF and placenta growth factor. The aim of this study was to assess the level of sFLT-1 in 35 children and adolescents with β-TI, correlating it with markers of hemolysis and iron overload as well as cardiopulmonary complications. Patients were studied focusing on the history of cardiac disease, splenectomy, transfusion, chelation/hydroxyurea therapy, serum ferritin, and sFLT-1 levels. Echocardiography and measurement of carotid intima–media thickness (CIMT) were done for all participants. Soluble fms-like tyrosine kinase 1 was significantly higher in TI patients compared to the control group (median [interquartile range], 110 [80-155] pg/mL versus 70 [60-90] pg/mL; P < .001). Splenectomized patients and those who had pulmonary hypertension risk or heart disease had higher sFLT-1 levels than those without ( P < .001). The sFLT-1 cutoff value that differentiates patients with and without pulmonary hypertension risk or heart disease was determined. Soluble fms-like tyrosine kinase 1 was lower among patients who received chelation therapy and/or hydroxyurea. Significant positive relations were observed between sFLT-1 and lactate dehydrogenase, serum ferritin, liver iron concentration, tricuspid regurgitant jet velocity, and CIMT. We suggest that sFLT-1 represents a link between angiogenesis, endothelial dysfunction, and subclinical atherosclerosis. Measurement of sFLT-1 as a marker of vascular dysfunction in β-TI may provide utility for early identification of patients at increased risk of cardiopulmonary complications.

Heart failure in haemoglobinopathies: pathophysiology, clinical phenotypes, and management

Hereditary haemoglobinopathies, mainly beta-thalassemia and sickle cell disease, constitute the most common monogenic disorders in humans, and although once geographically confined, they are currently globally distributed. They are demanding clinical entities that require multidisciplinary medical management. Despite their genotypic and phenotypic heterogeneity, the haemoglobinopathies share several similarities in pathophysiology, clinical manifestations, therapeutic requirements, and complications, among which heart failure (HF) represents a leading cause of mortality and morbidity. However, haemoglobinopathies have generally been addressed in a rather fragmentary manner. A unifying approach focusing on the underlying similarities of HF attributes in the two main entities might contribute to their better understanding, characterization, and management. In the present review, we attempt such an approach to the pathophysiology, clinical phenotypes, and management of HF in haemoglobinopathies.

Increased Red Blood Cell Stiffness Increases Pulmonary Vascular Resistance and Pulmonary Arterial Pressure

Patients with sickle cell anemia (SCD) and pulmonary hypertension (PH) have a significantly increased risk of sudden death compared to patients with SCD alone. Sickled red blood cells (RBCs) are stiffer, more dense, more frequently undergo hemolysis, and have a sixfold shorter lifespan compared to normal RBCs. Here, we sought to investigate the impact of increased RBC stiffness, independent of other SCD-related biological and mechanical RBC abnormalities, on the hemodynamic changes that ultimately cause PH and increase mortality in SCD. To do so, pulmonary vascular impedance (PVZ) measures were recorded in control C57BL6 mice before and after ∼50 μl of blood (Hct = 45%) was extracted and replaced with an equal volume of blood containing either untreated RBCs or RBCs chemically stiffened with glutaraldehyde (Hct = 45%). Chemically stiffened RBCs increased mean pulmonary artery pressure (mPAP) (13.5 ± 0.6 mmHg at baseline to 23.2 ± 0.7 mmHg after the third injection), pulmonary vascular resistance (PVR) (1.23 ± 0.11 mmHg*min/ml at baseline to 2.24 ± 0.14 mmHg*min/ml after the third injection), and wave reflections (0.31 ± 0.02 at baseline to 0.43 ± 0.03 after the third injection). Chemically stiffened RBCs also decreased cardiac output, but did not change hematocrit, blood viscosity, pulmonary arterial compliance, or heart rate. The main finding of this study is that increased RBC stiffness alone affects pulmonary pulsatile hemodynamics, which suggests that RBC stiffness plays an important role in the development of PH in patients with SCD.

Arterial Stiffness Impairment in Sickle Cell Disease Associated With Chronic Vascular Complications

Background:

Although a blood genetic disease, sickle cell disease (SCD) leads to a chronic vasculopathy with multiple organ involvement. We assessed arterial stiffness in SCD patients and looked for associations between arterial stiffness and SCD-related vascular complications.

Methods:

The CADRE (Coeur Artères et Drepanocytose, ie, Heart Arteries and Sickle Cell Disease) study prospectively recruited pediatric and adult SCD patients and healthy controls in Cameroon, Ivory Coast, Gabon, Mali, and Senegal. Patients underwent clinical examination, routine laboratory tests (complete blood count, serum creatinine level), urine albumin/creatinine ratio measure, and a measure of carotid-femoral pulse wave velocity (cf-PWV) and augmentation index (AI) at a steady state. The clinical and biological correlates of cf-PWV and AI were investigated by using a multivariable multilevel linear regression analysis with individuals nested in families further nested in countries.

Results:

Included were 3627 patients with SCD and 943 controls. Mean cf-PWV was lower in SCD patients (7.5±2.0 m/s) than in controls (9.1±2.4 m/s, P <0.0001), and lower in SS-Sβ 0 than in SC-Sβ + phenotypes. AI, corrected for heart rate, increased more rapidly with age in SCD patients and was higher in SCD than in control adults. cf-PWV and AI were independently associated with age, sex, height, heart rate, mean blood pressure, hemoglobin level, country, and hemoglobin phenotype. After adjustment for these correlates, cf-PWV and AI were associated with the glomerular filtration rate and osteonecrosis. AI was also associated with stroke, pulmonary hypertension, and priapism, and cf-PWV was associated with microalbuminuria.

Conclusions:

PWV and AI are deeply modified in SCD patients in comparison with healthy controls. These changes are independently associated with a lower blood pressure and a higher heart rate but also with the hemoglobin phenotype. Moreover, PWV and AI are associated with several SCD clinical complications. Their prognostic value will be assessed at follow-up of the patients.

Morbidity and mortality of adult patients with congenital dyserythropoietic anemia type I

Congenital dyserythropoietic anemia type I (CDAI) is a rare autosomal recessive disease characterized by macrocytic anemia, ineffective erythropoiesis, and secondary hemochromatosis. To better define the natural history of the disease among adult patients, we studied 32 Bedouin patients (median age 34 yr; range 21-60) all carrying the same CDAN1 founder mutation. Follow-up studies included complete blood count, blood chemistry, abdominal ultrasound, echocardiography, and T2*MRI. Main complications were due to anemia and ineffective erythropoiesis [osteoporosis (8/9, 89%), cholelithiasis (21/30, 70%), pulmonary arterial hypertension (PAH) (6/25, 24%)] and iron overload [hypothyroidism (9/24, 38%), and diabetes mellitus (6/32, 19%)]. T2* MRI revealed increased liver iron but no cardiac iron (13/13). Anemia improved in the majority of patients who underwent splenectomy (5/6). Three patients died (9%) at the age of 46-56 due to PAH (1) and sepsis (2). All previously underwent splenectomy. Analyzing both our patients and the 21 patients previously described by Heimpel et al. (Blood 107:334, 2006), we conclude that adults with CDA I suffer significant morbidity and mortality. Careful monitoring of iron overload and prompt iron chelation therapy is mandatory. Due to possible complications and inconsistent response to splenectomy α-interferon, transfusion therapy or stem cell transplantation should be considered as alternatives to this procedure in severely affected patients.

Abnormalities in aortic properties: a potential link between left ventricular diastolic function and ventricular-aortic coupling in sickle cell disease

Left ventricular (LV) diastolic dysfunction in patients with sickle cell disease (SCD) is associated with increased mortality. However, its mechanisms are not well known, preventing the development of effective therapies. We hypothesized that patients with SCD have altered aortic properties despite normal blood pressure, which may contribute towards the development of diastolic dysfunction. We studied 31 stable adult patients with SCD (32 ± 7 years) and 12 healthy controls of similar age (29 ± 10 years) who underwent echocardiography and cardiovascular magnetic resonance (CMR) imaging on the same day. Echocardiographic measurements of mitral inflow and mitral annulus velocities were used to evaluate LV diastolic function. CMR imaging included standard LV function evaluation and myocardial tissue characterization as well as velocity-encoded images of the ascending aorta to measure aortic diastolic cross-sectional area, distensibility, as well as peaks and volumes of the global, forward and backward blood flow rate. Compared to controls, SCD patients had increased aortic diastolic area, global stroke volume, and both forward and backward flow, while aortic distensibility and peripheral blood pressure were similar. Furthermore, peak backward flow rate and volume were able to discriminate between patients with and without diastolic dysfunction. Our findings show that some aortic properties are altered in SCD patients and may be associated with diastolic dysfunction despite normal systolic blood pressure. If confirmed in larger studies, these aortic changes could be a novel therapeutic target to prevent or delay the development of LV diastolic dysfunction in SCD and thus potentially improve outcomes in these patients.

Haematological determinants of cardiac involvement in adults with sickle cell disease

AIMS

Cardiac involvement is common in sickle cell disease (SCD). Studies are needed to establish haematological determinants of this involvement and prognostic markers. The aim of the study was to identify haematological factors associated with cardiac involvement in SCD and their impact on prognosis.

METHODS AND RESULTS

This longitudinal observational study was performed on 1780 SCD patients with SS or S-β(0)-thalassemia referred to our centre. Six hundred fifty-six met our inclusion criteria (availability of a blood-workup and echocardiogram obtained <1 year apart, no heart valve surgery and no current pregnancy). Median age was 31 (interquartile range, 25-40) years, and median haemoglobin (Hb) was 87 (80-95)g/L. Left ventricular (LV) dilation, left atrial dilation, cardiac index (CI) >4 L/min/m(2), LV ejection fraction <55%, and tricuspid regurgitant velocity (TRV) ≥2.5 m/s were found in 35, 78, 23, 8.5, and 17% of patients, respectively. Compared with other patients, those in the fourth quartiles (Q4) of LV end-diastolic dimension index (LVEDDind) and left atrial dimension index (LADind) and those with high CI had significantly lower Hb, % foetal Hb (HbF), and red blood cell (RBC) counts; and significantly higher lactate dehydrogenase, bilirubin, and %dense RBCs. Independent haematologic determinants of Q4 LVEDDind and LADind were low RBC count and %HbF; high %dense RBCs were associated with LADind. Low %HbF and RBC count were associated with high CI. High %dense RBCs or no α-thalassemia gene deletion was associated with greater severity of anaemia and cardiac dilation and with higher CI. During the median follow-up of 48 (32-59) months, 50 (7.6%) patients died. Tricuspid regurgitant velocity ≥ 2.5 m/s was a predictor of mortality. The risk of death increased four-fold when left ventricular ejection fraction <55% was present also (P = 0.0001).

CONCLUSION

Cardiac dilation and CI elevation in patients with SCD are associated with haematologic variables reflecting haemolysis, RBC rigidity, and blood viscosity. Tricuspid regurgitant velocity ≥ 2.5 and LV dysfunction (even mild) predict mortality.

Growth differentiation factor-15 in children and adolescents with thalassemia intermedia: Relation to subclinical atherosclerosis and pulmonary vasculopathy

BACKGROUND

Heart disease is the leading cause of mortality and one of the main causes of morbidity in β-thalassemia. Growth differentiation factor-15 (GDF-15), a member of the transforming growth factor-β superfamily, is a marker of ineffective erythropoiesis in several anemias.

AIM

To determine GDF-15 levels in children and adolescents with TI and the relation to hemolysis, iron overload and cardiovascular complications.

METHODS

GDF-15 was measured in 35 TI patients without symptoms for heart disease and correlated to echocardiographic parameters and carotid intima media thickness (CIMT).

RESULTS

GDF-15 levels were significantly higher in TI patients compared with controls (p < 0.001). Transfusion dependent patients had higher GDF-15 than non-transfusion dependent patients. TI patients with splenectomy, pulmonary hypertension risk, and heart disease had higher GDF-15 levels than those without. GDF-15 was lower among hydroxyurea-treated patients. Multiple linear regression analysis revealed that transfusion index (p=0.012), serum ferritin (p < 0.001), tricuspid regurgitant jet velocity (p < 0.001), ejection fraction (p=0.01) and CIMT (p=0.007) were independently related to GDF-15. According to ROC curve analysis, the cutoff value of GDF-15 at 1500 pg/mL could differentiate patients with and without heart disease.

CONCLUSION

GDF-15 would identify TI patients at increased risk of pulmonary and cardiovascular complications as well as subclinical atherosclerosis.

The Role of the Carotid Doppler Examination in the Evaluation of Atherosclerotic Changes in β-Thalassemia Patients

BACKGROUND

Iron overload in patients with beta-thalassemia major (BTM) lead to alterations in the arterial structures and the thickness of the carotid arteries. Doppler ultrasound scanning of extra-cranial internal carotid arteries is non-invasive and relatively quick to perform and may identify children at increased risk of stroke that would otherwise be missed. Increased carotid artery intima media thickness (CIMT) is a structural marker for early atherosclerosis and correlates with the vascular risk factors and to the severity and extent of coronary artery disease.

OBJECTIVE

To evaluate the role of carotid Doppler examination and CIMT measurement as a predictor of atherosclerotic changes in BTM children with iron overload.

PATIENTS AND METHODS

Sixty two children with BTM and, thirty age and sex matched normal controls were included. Complete blood count, ferritin, serum cholesterol were done, as well as carotid Doppler ultrasonography to measure the CIMT in both patients and controls.

RESULTS

CIMT of thalassemic patients was significantly increased compared to controls (p=0.001). There was a significant positive correlation between CIMT and patient's age, the duration from first blood transfusion, serum cholesterol and, iron overload parameters as serum ferritin, frequency of blood transfusion, iron chelation. The length of the transfusion period was the highest risk factor, and an inadequate iron chelation was a further risk factor. Significant negative correlation was found between CIMT and hematocrit value while no significant correlation was found between CIMT and weight, height, BMI centiles and Hb level.

CONCLUSION

Carotid Doppler is very useful in measurement of CIMT that increased in thalassemic patients that shows a strong relationship with features of iron overload. Routine Doppler measurement of CIMT in these patients is recommended to predict early atherosclerotic changes as well as in follow-up.

Endothelial Function and Vascular Properties in Children with Sickle Cell Disease

BACKGROUND

Sickle cell disease (SCD) is an inherited disorder characterized by recurrent painful crises with ischemia resulting from vascular occlusion. Adults with SCD have increased arterial stiffness and reduced flow-mediated dilation (FMD), due to impaired release of substances such as nitric oxide.

AIM

We aimed to assess the vascular properties of carotid and brachial arteries in children with SCD compared with a control group without cardiovascular risk factors.

METHODS

Thirty patients with SCD, mean age 12.3 ± 4.5 years, were prospectively enrolled. A control group was made up of 30 age- and gender-matched healthy subjects. Carotid intima-media thickness (IMT), cross-sectional compliance (CSC), cross-sectional distensibility (CSD), diastolic wall stress (DWS), incremental elastic modulus (Einc), and FMD were determined in both groups.

RESULTS

There was no significant difference in FMD between the two groups (8.2 ± 5.0% in the SCD group vs. 9.3 ± 4.2% in the control group, P = 0.15). There was no significant correlation between FMD and age, hemoglobin, LDH level, or transcranial Doppler findings. CSD was significantly elevated in the SCD group (0.96 ± 0.44 vs. 0.59 ± 0.21, P = 0.0002), whereas DWS and Einc were significantly lower in the SCD group. CSC did not differ significantly between the two groups.

CONCLUSIONS

Children with SCD have no marked endothelial dysfunction or change in arterial stiffness. These manifestations may be related to disease severity and duration. Changes may become evident later in life as the disease progresses.

Guidelines for diagnosis and management of Beta-thalassemia intermedia

Beta-thalassemia intermedia (β-TI) is a genetic variant of beta-thalassemias with a clinical disorder whose severity falls between thalassemia minor and thalassemia major. Different genetic defects are involved in this disorder and, based on severity of disease, clinical complications like skeletal deformities and growth retardation, splenomegaly, extramedullary hematopoiesis, heart failure, and endocrine disorders may be present in untreated patients. Precise diagnosis and management are essential in these patients for prevention of later clinical complications. Diagnosis of TI is based on clinical and laboratory data. There are some treatment strategies like modulation of gamma-globulin chain production with hydroxyurea or other drugs, transfusion, splenectomy, and stem cell transplantation. Iron chelation therapy is also needed in many of these patients even if they are not transfused. The aim of this manuscript is to review the clinical manifestations, complications, genetic defects, and unmet treatments needs in TI.

Atherogenesis and iron: from epidemiology to cellular level

Iron accumulates in human atherosclerotic lesions but whether it is a cause or simply a downstream consequence of the atheroma formation has been an open question for decades. According to the so called "iron hypothesis," iron is believed to be detrimental for the cardiovascular system, thus promoting atherosclerosis development and progression. Iron, in its catalytically active form, can participate in the generation of reactive oxygen species and induce lipid-peroxidation, triggering endothelial activation, smooth muscle cell proliferation and macrophage activation; all of these processes are considered to be proatherogenic. On the other hand, the observation that hemochromatotic patients, affected by life-long iron overload, do not show any increased incidence of atherosclerosis is perceived as the most convincing evidence against the "iron hypothesis." Epidemiological studies and data from animal models provided conflicting evidences about the role of iron in atherogenesis. Therefore, more careful studies are needed in which issues like the source and the compartmentalization of iron will be addressed. This review article summarizes what we have learnt about iron and atherosclerosis from epidemiological studies, animal models and cellular systems and highlights the rather contributory than innocent role of iron in atherogenesis.

Arterial stiffness and pulse wave reflection in young adult heterozygous sickle cell carriers

Objective: Pulse wave velocity (PWV) and aortic augmentation index (AI) are indicators of arterial stiffness. Pulse wave reflection and arterial stiffness are related to cardiovascular events and sickle cell disease. However, the effect of these parameters on the heterozygous sickle cell trait (HbAS) is unknown. The aim of this study is to evaluate the arterial stiffness and wave reflection in young adult heterozygous sickle cell carriers.

Materials and Methods: We enrolled 40 volunteers (20 HbAS cases, 20 hemoglobin AA [HbAA] cases) aged between 18 and 40 years. AI and PWV values were measured by arteriography.

Results: Aortic blood pressure, aortic AI, and brachial AI values were significantly higher in HbAS cases compared to the control group (HbAA) (p=0.033, 0.011, and 0.011, respectively). A statistically significant positive correlation was found between aortic pulse wave velocity and mean arterial pressure, age, aortic AI, brachial AI, weight, and low-density lipoprotein levels (p=0.000, 0.017, 0.000, 0.000, 0.034, and 0.05, respectively) in the whole study population. Aortic AI and age were also significantly correlated (p=0.026). In addition, a positive correlation between aortic PWV and systolic blood pressure and a positive correlation between aortic AI and mean arterial pressure (p=0.027 and 0.009, respectively) were found in HbAS individuals. Our study reveals that mean arterial pressure and heart rate are independent determinants for the aortic AI. Mean arterial pressure and age are independent determinants for aortic PWV.

Conclusion: Arterial stiffness measurement is an easy, cheap, and reliable method in the early diagnosis of cardiovascular disease in heterozygous sickle cell carriers. These results may depend on the amount of hemoglobin S in red blood cells. Further studies are required to investigate the blood pressure changes and its effects on arterial stiffness in order to explain the vascular aging mechanism in the HbAS trait population.

Conflict of interest:None declared.

Flow cytometric assessment of circulating platelet and erythrocytes microparticles in young thalassemia major patients: relation to pulmonary hypertension and aortic wall stiffness

Heart disease is the leading cause of mortality and morbidity in β-thalassemia major (β-TM). Aggregability of abnormal red cells and membrane-derived microparticles (MPs) stemming from activated platelets and erythrocytes are responsible for thrombotic risk. We measured platelet and erythrocyte MPs (PMPs and ErMPs) in 60 young β-TM patients compared with 40 age- and sex-matched healthy controls and assessed their relation to clinicopathological characteristics and aortic elastic properties. Patients were studied stressing on transfusion history, splenectomy, thrombotic events, chelation therapy, hematological and coagulation profiles, flow cytometric measurement of PMPs (CD41b(+) ) and ErMPs (glycophorin A(+) ) as well as echocardiographic assessment of aortic elastic properties. Aortic stiffness index and pulmonary artery pressure were significantly higher, whereas aortic strain and distensibility were lower in TM patients than controls (P < 0.001). Both PMPs and ErMPs were significantly elevated in TM patients compared with controls, particularly patients with risk of pulmonary hypertension, history of thrombosis, splenectomy or serum ferritin >2500 μg/L (P < 0.001). Compliant patients on chelation therapy had lower MPs levels than non-compliant patients (P < 0.001). PMPs and ErMPs were positively correlated to markers of hemolysis, serum ferritin, D-dimer, vWF Ag, and aortic stiffness, whereas negatively correlated to hemoglobin level and aortic distensibility (P < 0.05). We suggest that increased MPs may be implicated in vascular dysfunction, pulmonary hypertension risk, and aortic wall stiffness observed in thalassemia patients. Their quantification could provide utility for early detection of cardiovascular abnormalities and monitoring the biological efficacy of chelation therapy.

Altered vascular function, arterial stiffness, and antioxidant gene responses in pediatric thalassemia patients

Patients with thalassemia major are susceptible to cardiovascular complications by mechanisms not fully understood. Although overt cardiovascular complications usually occur after puberty, their underlying pathogenesis may begin much earlier. This study investigated whether there were early changes in vascular endothelial function and arterial stiffness in young patients with beta-thalassemia and hemoglobin E, and whether these changes were associated with oxidative stress and expression of antioxidant genes. The study recruited 30 pediatric patients and 30 age-matched control subjects. Compared with the control subjects, the patients had increased levels of oxidant biomarkers including malondialdehyde, protein carbonyl, and non-transferrin-bound iron and a decreased glutathione redox ratio. There were clear signs of vascular endothelial dysfunction and increased arterial stiffness, as shown by marked suppression of forearm blood flow after reactive hyperemia and increased pulse-wave velocity in the trunk and legs. The changes in FBF were associated with oxidative stress markers and free iron. An adaptive antioxidant gene response was activated in blood mononuclear cells, as shown by upregulation of GCLC and Bach-1 mRNA but downregulation of heme oxygenase-1 and thioredoxin mRNA. The results highlight the vascular changes seen even in young patients during treatment. These changes were associated with oxidative stress and suggest an adaptive response that serves to protect host cells from further oxidative damage.

Atherosclerosis in sickle cell disease - a review

Acute, vaso-occlusive crises are the most common and earliest clinical manifestations of sickle cell disease. Recent thoughts about development of atherosclerosis as a result of this disease are presented. Current insights into the pathogenesis of atherosclerosis in sickle cell disease are reviewed, in particular the role of endothelial dysfunction, homocysteine and platelets. Common and uncommon sites of atherosclerosis are described. Radiological assessment and potential therapeutic agents to slow the progression of atherosclerosis are discussed. Finally, treatment of atherosclerosis in certain sites is evaluated and reviewed.

Hemodynamic characteristics and predictors of pulmonary hypertension in patients with sickle cell disease

Pulmonary hypertension is a common co-morbidity of sickle cell disease with an associated increased mortality risk, but its etiology is not well-understood. To evaluate the hemodynamic characteristics, clinical predictors, and cardiovascular manifestations of elevated pulmonary arterial pressure in this population, we performed noninvasive hemodynamic assessments of 135 patients with sickle cell disease using Doppler echocardiography. A diagnosis of pulmonary hypertension was determined by gender-, age-, and body mass index-specific normal reference ranges for tricuspid regurgitation jet velocities (TRVs). A high TRV was noted in 34 patients (25%). Pulmonary vascular resistance was elevated in only 2 (6%) of the 34 patients with suspected pulmonary hypertension but was significantly greater than in those with normal TRV. On univariate regression, the TRV correlated with age, body mass index, left atrial pressure, and right ventricular stroke volume and was negatively associated with hemoglobin and glomerular filtration rate. The left atrial pressure, right ventricular stroke volume, and hemoglobin remained independent predictors of TRV in a multivariate model. A greater TRV was also associated with larger right ventricular and right atrial chamber sizes and greater N-terminal probrain natriuretic peptide levels. In conclusion, our results suggest that the mild elevation in TRV often observed in patients with sickle cell disease is rarely associated with a high pulmonary vascular resistance and that multiple factors-including the compensatory high output state associated with anemia, pulmonary venous hypertension, and pulmonary vasculopathy-can contribute to an elevated pulmonary arterial pressure in these patients.

Hemin causes mitochondrial dysfunction in endothelial cells through promoting lipid peroxidation: the protective role of autophagy

The hemolysis of red blood cells and muscle damage results in the release of the heme proteins myoglobin, hemoglobin, and free heme into the vasculature. The mechanisms of heme toxicity are not clear but may involve lipid peroxidation, which we hypothesized would result in mitochondrial damage in endothelial cells. To test this, we used bovine aortic endothelial cells (BAEC) in culture and exposed them to hemin. Hemin led to mitochondrial dysfunction, activation of autophagy, mitophagy, and, at high concentrations, apoptosis. To detect whether hemin induced lipid peroxidation and damaged proteins, we used derivatives of arachidonic acid tagged with biotin or Bodipy (Bt-AA, BD-AA). We found that in cells treated with hemin, Bt-AA was oxidized and formed adducts with proteins, which were inhibited by α-tocopherol. Hemin-dependent mitochondrial dysfunction was also attenuated by α-tocopherol. Protein thiol modification and carbonyl formation occurred on exposure and was not inhibited by α-tocopherol. Supporting a protective role of autophagy, the inhibitor 3-methyladenine potentiated cell death. These data demonstrate that hemin mediates cytotoxicity through a mechanism which involves protein modification by oxidized lipids and other oxidants, decreased respiratory capacity, and a protective role for the autophagic process. Attenuation of lipid peroxidation may be able to preserve mitochondrial function in the endothelium and protect cells from heme-dependent toxicity.

Cardiac function and iron chelation in thalassemia major and intermedia: a review of the underlying pathophysiology and approach to chelation management

Heart disease is the leading cause of mortality and one of the main causes of morbidity in beta-thalassemia. Patients with homozygous thalassemia may have either a severe phenotype which is usually transfusion dependent or a milder form that is thalassemia intermedia. The two main factors that determine cardiac disease in homozygous β thalassemia are the high output state that results from chronic tissue hypoxia, hypoxia-induced compensatory reactions and iron overload. The high output state playing a major role in thalassaemia intermedia and the iron load being more significant in the major form. Arrhythmias, vascular involvement that leads to an increased pulmonary vascular resistance and an increased systemic vascular stiffness and valvular abnormalities also contribute to the cardiac dysfunction in varying degrees according to the severity of the phenotype. Endocrine abnormalities, infections, renal function and medications can also play a role in the overall cardiac function. For thalassaemia major, regular and adequate blood transfusions and iron chelation therapy are the mainstays of management. The approach to thalassaemia intermedia, today, is aimed at monitoring for complications and initiating, timely, regular transfusions and/or iron chelation therapy. Once the patients are on transfusions, then they should be managed in the same way as the thalassaemia major patients. If cardiac manifestations of dysfunction are present in either form of thalassaemia, high pre transfusion Hb levels need to be maintained in order to reduce cardiac output and appropriate intensive chelation therapy needs to be instituted. In general recommendations on chelation, today, are usually made according to the Cardiac Magnetic Resonance findings, if available. With the advances in the latter technology and the ability to tailor chelation therapy according to the MRI findings as well as the availability of three iron chelators, together with increasing the transfusions as need, it is hoped that the incidence of cardiac dysfunction in these syndromes will be markedly reduced. This of course depends very much on the attention to detail with the monitoring and the cooperation of the patient with both the recommended investigations and the prescribed chelation.

Cardiac involvement in sickle beta-thalassemia

Cardiovascular involvement is a leading cause of mortality and morbidity in patients with inherited hemoglobinopathies, but it has not been adequately assessed in sickle beta-thalassemia. We evaluated 115 sickle beta-thalassemia patients, aged 34 +/- 14 years, along with 50 healthy controls, by resting echocardiography. Patients with systolic left ventricular (LV) dysfunction or severe pulmonary hypertension (PHT) also underwent left and right cardiac catheterization and cardiac magnetic resonance imaging (CMR). Left and right chamber dimensions, LV mass, and cardiac index were significantly higher in patients compared to controls (p < 0.001 in most cases). Three patients (2.9%) had reduced LV ejection fraction (<55%); mean LV ejection fraction was significantly lower in patients (p < 0.001). Left and right ventricular systolic tissue Doppler indices and LV diastolic tissue Doppler indices were also impaired in patients. All three patients with systolic LV dysfunction had normal coronary arteries and mild myocardial iron load (CMR T2* values, 18-25 ms). Systolic pulmonary artery pressure was significantly higher in patients compared to controls (p = 0.002); PHT was present in 28 patients (27%), while severe PHT in three (2.9%). In three patients with severe PHT, only one had impaired LV ejection fraction and increased pulmonary wedge pressure. Overall, three patients (2.9%) had a history of heart failure, two with systolic LV dysfunction, and one with severe PHT. Cardiac involvement in sickle beta-thalassemia concerns biventricular dilatation and dysfunction along with PHT, leading to congestive heart failure.

Endothelial dysfunction and oxidant status in pediatric patients with hemoglobin E-beta thalassemia

Thalassemia major is characterized by anemia, iron overload, and oxidant damage to major organs, especially the cardiovascular system. Oxidative stress is ultimately involved in endothelial dysfunction, a condition which is evident in adults suffering from various cardiovascular diseases including thalassemia. We investigated endothelial function in pediatric patients with hemoglobin E-beta thalassemia (HbE-beta thalassemia), who have been exposed to excessive iron and oxidative stress for much shorter period than adults with thalassemia. We recruited 22 blood transfusion-dependent HbE-beta thalassemia patients aged 11.8 +/- 2.9 years and 20 healthy controls aged 12.1 +/- 1.7 years. Oxidant status was determined, and endothelial function was assessed by a forearm blood flow technique. Oxidative stress was increased in the thalassemic patients, as blood glutathione (GSH) and ratios of reduced GSH to GSH disulfide were markedly reduced, and superoxide anion released from blood cells was highly elevated. Oxidative stress response, assessed by gamma-glutamylcysteine ligase activity, was increased approximately twofold in thalassemia patients. Basal forearm blood flow was significantly increased in patients compared with controls (7.3 +/- 1.8 vs 6.0 +/- 1.8 ml/100 ml tissue/min, respectively), whereas forearm vasodilatory response to reactive hyperemia was depressed by 50% in patients compared with controls. Endothelial function is impaired in young thalassemia patients, and impaired endothelial function is associated with oxidant stress.

Elastic Properties of the Ascending Aorta in Patients with ?-Thalassemia Major

BACKGROUND

Beta-thalassemia major (beta-TM) is a congenital hemolytic disorder characterized by impaired left ventricular and endothelial function. However, elastic properties of the aorta have not been sufficiently investigated in patients with beta-TM. We investigated whether beta-TM is related to impaired ascending aortic elastic properties.

METHODS

We studied 36 patients with beta-TM (age: 15.8 +/- 2.6 years) and 30 age- and sex-matched control subjects by echocardiography. Aortic elastic indexes, aortic strain (%), distensibility (cm(2) dyn(-1) 10(-3)), and stiffness index were calculated from the echocardiographically derived thoracic aortic diameters (mm/m(2)), and the measurement of pulse pressure obtained by cuff sphygmomanometry.

RESULTS

Patients versus control subjects had increased aortic diameters (P < 0.001), lower mean aortic strain (9 +/- 3.6 vs. 14.9 +/- 3.2, P < 0.001) and distensibility (0.6 +/- 0.36 vs. 0.8 +/- 0.2, P < 0.012), and higher mean stiffness index (5.3 +/- 2.4 vs. 2.8 +/- 0.6, P < 0.001). Aortic elastic indexes were significantly associated with ferritin level, while stiffness index was significantly related to platelet count.

CONCLUSION

Elastic properties of ascending aorta are impaired in patients with beta-TM. Impaired functions of aorta may lead to deterioration of left ventricular function.