Arterial elastorrhexis: manifestation of a generalized elastic tissue disorder in beta-thalassaemia major

Use of strain, strain rate, tissue velocity imaging, and endothelial function for early detection of cardiovascular involvement in patients with beta-thalassemia

BACKGROUND

Global ventricular function often remains normal in patients with beta-thalassemia major (β-TM) until late. Tissue Doppler and strain imaging may be useful to assess regional myocardial function abnormalities in these patients.

METHODS

Systolic (Sm), early diastolic (Em), and late diastolic (Am) (Em/Am) myocardial velocities at basal lateral and septal left ventricular (LV) segments, strain (S), and strain rate (SR) in basal and mid LV, right ventricular (RV) and septum were measured in 30 patients (β-TM, 12.4 ± 5.2 years, serum ferritin 2603.1 μg/L) and twenty controls (12.5 ± 5.2 years). Flow-mediated dilatation (FMD) vasodilatation as a measure of endothelial function was also assessed.

RESULTS

Patients had significantly higher LV mass index (169.45 ± 61.14 vs. 104.66 ± 24.42; P = 0.009) while global LV Sm and diastolic function was similar to controls. Patients had significantly lower lateral Em velocity, Em (10.12 ± 1.16 vs. 17.9 ± 2.11; P = 0.002), Em/Am ratio (0.811 ± 0.192 vs. 2.06 ± 0.62; P = 0.001) at the basal lateral LV, lower strain values at the basal lateral LV (19.5 ± 4.17 vs. 24.196 ± 1.81; P = 0.002), mid lateral LV (19.07 ± 3.98 vs. 25.56 ± 2.62; P = 0.042), basal septum (17.04 ± 3.44 vs. 25.43 ± 2.53; P = 0.001), and mid septum (20.49 ± 5.34 vs. 24.45 ± 2.20; P = 0.001) as compared to controls. SR at the basal and mid segment of the lateral LV wall and at the basal and mid septum was also significantly lower in patients. SR in basal and mid RV although lower was not significantly different from controls. Patients also had significantly lower FMD (7.57 ± 3.16 vs. 18.08 ± 1.9, P = 0.018) implying endothelial dysfunction.

CONCLUSIONS

Tissue Doppler, strain and SR imaging are useful to quantify regional myocardial function in asymptomatic β-TM patients with preserved global Sm and diastolic function.

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.

The evaluation of carotid intima-media thickness in children with beta-thalassaemia major

BACKGROUND

Cardiovascular complications and vascular changes are common in patients with beta-thalassaemia major. The aim of this study is to investigate the common carotid artery intima-media thickness in children.

METHODS

The study population was consisted of 33 thalassaemic children (22 boys and 11 girls, with a median age of 8 years) and 30 healthy children for control (12 girls and 18 boys, with a median age of 8 years) who were matched for age and gender. Common carotid artery intima-media thickness of the children was measured.

RESULTS

The patients' age at diagnosis ranged from 0.25 to 2 years, with a median of 0.6 months. Their disease duration ranged from 4 to 13.75 years, with a median of 6.5 years. The patients' median common carotid artery intima-media thickness was significantly higher than controls - that is, 0.87 versus 0.74, with a p-value less than 0.005. The mean common carotid artery intima-media thickness value was positively correlated with disease duration (r = 0.535), with a p-value less than 0.01 and ferritin level (r = 0.501), with a p-value less than 0.01.

CONCLUSION

Owing to the nature of the disease, patients with beta-thalassaemia major should be considered to have an increased risk of early vascular alteration and atherosclerosis. For this reason, common carotid artery intima-media thickness measurement can be recommended as a non-invasive and early diagnostic method.

A mouse model of β-thalassemia shows a liver-specific down-regulation of Abcc6 expression

β-Thalassemia and pseudoxanthoma elasticum (PXE) are distinct genetic disorders. Yet, a dystrophic mineralization phenotype similar to PXE has frequently been associated with β-thalassemia or sickle cell anemia patients of Mediterranean descent. These calcifications are clinically and structurally identical to inherited PXE. As we previously excluded the presence of PXE-causing mutations in the ABCC6 gene of β-thalassemia patients with PXE manifestations, we hypothesized that a molecular mechanism independent of gene mutations either altered the ABCC6 gene expression or disrupted the biologic properties of its product in the liver or kidneys, which are the tissues with the highest levels of expression. To test this possibility, we investigated Abcc6 synthesis in the liver and kidneys of a β-thalassemia mouse model (Hbb(th3/+)). We found a progressive liver-specific down-regulation of the Abcc6 gene expression and protein levels by quantitative PCR, Western blotting, and immunofluorescence. The levels of Abcc6 protein decreased significantly at 6 months of age and stabilized at 10 months and older ages at ∼25% of the wild-type protein levels. We studied the transcriptional regulation of the Abcc6 gene in wild-type and Hbb(th3/+) mice, and we identified the erythroid transcription factor NF-E2 as the main cause of the transcriptional down-regulation using transcription factor arrays and chromatin immunoprecipitation. The Hbb(th3/+) mice did not develop spontaneous calcification as seen in the Abcc6(-/-) mice probably because the Abcc6 protein decrease occurred late in life and was probably insufficient to promote mineralization in the Hbb(th3/+) mouse C57BL/6J genetic background. Nevertheless, our result suggested that a similar decrease of ABCC6 expression occurs in the liver of β-thalassemia patients and may be responsible for their frequent PXE-like manifestations.

Comparison of vascular complications between conventional treatment and bone marrow transplantation for children with beta-thalassemia disease

Patients with ss-thalassemia may be predisposed to premature atherosclerosis due to vascular dysfunction. This is observed in adults. Whether atherosclerosis changes in ss-thalassemia disease (BTD) occur early in childhood is not clear. To prevent cardiovascular complications, this needs evaluation. Moreover, it remains uncertain whether curative treatment with bone marrow transplantation (BMT) would improve this vascular alteration. For this study, 37 ss-thalassemia children age 10.1 +/- 2.7 years were classified into group 1 (25 children with BTD treated conventionally) and group 2 (12 children with BTD who underwent BMT). A control group of 29 age-matched healthy children were studied simultaneously. The carotid stiffness index and intima-media thickness (IMT) were measured. Group1 had a greater arterial stiffness index than the control subjects (4.57 +/- 1.78 vs. 2.87 +/- 1.07; p < 0.001). The carotid IMT was significantly greater in both BTD groups than in the control group (group 1: 0.45 +/- 0.03 vs. 0.34 +/- 0.04 mm; p < 0.001; group 2: 0.43 +/- 0.03 vs. 0.34 +/- 0.04 mm; p < 0.001). Carotid IMT and arterial stiffness are increased in conventionally treated children with ss-thalassemia, suggesting an early atherosclerotic change in these children, whereas children with BTD who underwent BMT had an increased carotid IMT but normal arterial stiffness.

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.

Stiffness of the abdominal aorta in beta-thalassemia major patients related with body iron load

OBJECTIVES

Increased iron stores have been implicated in the association with increased risk of cardiovascular events. We evaluated whether the abdominal aortic stiffness was altered in the patients with beta-thalassemia major in relation with body iron load.

METHODS

Sixty-two (32 males and 30 females) beta-thalassemia major patients aged 16.47 +/- 4.8 years were enrolled into the study. Healthy 52 subjects matched for age and sex were recruited as controls. In all subjects, hemoglobin, fasting glucose, cholesterol, high-density lipoprotein-cholesterol, and low-density lipoprotein-cholesterol levels were measured. The average serum ferritin level and liver iron concentration (LIC) were assessed in thalassemia patients. Left ventricular function and mass were evaluated echocardiographically and aortic strain (S), pressure strain elastic modulus (Ep), and normalized Ep (Ep*), aortic distensibility (DIS), and beta stiffness index (beta index) were calculated in all subjects.

RESULTS

There was no statistically significant difference between the study and control groups in sex, mean age, body mass index, heart rate, and systolic blood pressure (P > 0.05). However, pulse pressure and left ventricular mass index (LVMI) were found higher in thalassemia major patients compared with the control group. In beta-thalassemia major patients S (0.21 +/- 0.027 vs. 0.26 +/- 0.017, P < 0.0001) and DIS (1.07 +/- 0.25 vs. 1.56 +/- 0.37, P < 0.0001) were significantly lower compared with the control group. However, Ep (196.9 +/- 44.86 vs. 134.20 +/- 29.10, P < 0.0001), Ep* (3.26 +/- 0.98 vs. 2.04 +/- 0.60, P < 0.0001), and beta index (2.44 +/- 0.58 vs. 1.61 +/- 0.37, P < 0.0001) were significantly higher in beta-thalassemia patients than controls. There was a statistically significant negative correlation between LIC and S, DIS. There was also negative correlation between LVMI and S. However, there was a statistically significant positive correlation between LIC and Ep, Ep*.

CONCLUSIONS

Increased abdominal aortic stiffness was detected in beta-thalassemia major patients and this increase in arterial stiffness correlated with LIC and LVMI.

Ventriculo-vascular interactions in patients with beta thalassaemia major

OBJECTIVES

To determine potential interactions between the heart and arterial system in patients with beta thalassaemia major.

DESIGN AND PATIENTS

Vascular compliance, systemic vascular resistance, and left ventricular (LV) contractility was determined in 34 asymptomatic thalassaemia patients at 2-4 hours after blood transfusion and also in 34 age and sex matched controls using a non-invasive device. The results were compared between groups and inter-relationships between LV contractility and indices of vascular load were explored.

SETTING

Tertiary paediatric cardiac centre.

RESULTS

When compared with controls, patients had greater systemic vascular resistance (1633 (259) v 1377 (276) dynes/s/cm5, p < 0.001) and effective arterial elastance (E(a)) (1.86 (0.25) v 1.65 (0.29) mm Hg/ml, p = 0.001), an index of combined pulsatile and static vascular load. On the other hand, their systolic blood pressure (104 (9) v 112 (13) mm Hg, p = 0.006), pulse pressure (45 (9) v 57 (10) mm Hg, p < 0.001), adjusted systemic vascular compliance (1.21 (0.09) v 1.37 (0.14), p < 0.001), adjusted brachial artery distensibility (21 (0.29) v 7.95 (0.29)%/mm Hg, p < 0.001) and LV+dP/dt (1059 (183) v 1239 (237) mm Hg/s, p = 0.001) were significantly lower. Significant determinants of LV contractility, as reflected by LV+dP/dt, were age (standardised beta = -0.24, p = 0.003), body mass index (standardised beta = -0.34, p = 0.004), systolic blood pressure (standardised beta = 0.90, p < 0.001), and effective E(a) (standardised beta = -0.50, p < 0.001) (model R2 = 0.69). No significant correlation existed between serum ferritin concentration and any of the cardiac or vascular indices.

CONCLUSION

An unfavourable ventriculo-vascular interaction, as characterised by impaired cardiac contractility and increased static and pulsatile vascular load, occurs in patients with beta thalassaemia major.

Rupture of chordae tendineae in patients with β-thalassemia

Cardiac disease is the primary cause of mortality in beta-thalassemia patients. Except for ventricular dysfunction and pulmonary hypertension that represent the main forms of heart disease in these patients, valvular abnormalities including valvular regurgitation, endocardial thickening and calcification and mitral valve prolapse have also been described. Here we present two patients with thalassemia major and mitral chordal rupture, a previously undescribed abnormality in this population. Pathogenesis of this finding may involve thalassemia-related pseudoxanthoma elasticum-like syndrome, a diffuse elastic tissue defect, which is observed with a notable frequency in these patients and has been associated with numerous cardiovascular complications, including valvular ones.

Arterial stiffness and endothelial function in patients with beta-thalassemia major

BACKGROUND

Increased iron store has been linked to risk of cardiovascular disease. Structural alterations of arteries in beta-thalassemia major patients and in vitro functional disturbance of vascular endothelial cells by thalassemic serum have been described. We sought to determine whether arterial stiffness and endothelial function are altered in vivo.

METHODS AND RESULTS

Thirty thalassemia patients (16 male) aged 22.2+/-7.4 years were recruited. Left ventricular (LV) mass and function were assessed echocardiographically. Carotid and brachioradial artery stiffness was assessed by stiffness index and pulse-wave velocity (PWV), respectively. Brachial artery endothelial function was assessed by vascular response to reactive hyperemia (flow-mediated dilation [FMD]) and sublingual glyceryl trinitrate. These indexes were compared with those of 30 age- and sex-matched controls. None of the patients had LV systolic or diastolic dysfunction. When compared with controls, patients had greater absolute (113.8+/-38.0 versus 109.0+/- 32.6 g, P=0.04) and indexed (82.4+/-17.5 versus 66.7+/-12.7 g/m(2), P<0.001) LV mass, carotid artery stiffness index (8.1+/-3.5 versus 5.5+/-1.6, P<0.001), and brachioradial PWV (8.9+/-2.4 versus 7.9+/-1.7 m/s, P= 0.03). Their FMD was impaired (3.5+/-3.3% versus 8.8+/-3.9%, P<0.001), whereas glyceryl trinitrate- mediated dilation was preserved (17.9+/-7.6% versus 16.3+/-6.1%, P=0.40). Both stiffness index and PWV correlated inversely with magnitude of FMD (r=-0.40, P=0.03; r=-0.41, P=0.03) and positively with indexed LV mass (r=0.50, P=0.005; r=0.40, P=0.027). Nonetheless, no significant correlation existed between ferritin level and carotid stiffness, PWV, or FMD.

CONCLUSIONS

Increased arterial stiffness, endothelial dysfunction, and LV hypertrophy occur in patients with beta-thalassemia major, which may result in reduction of mechanical efficiency of the heart.

Cardiovascular involvement in thalassaemic patients with pseudoxanthoma elasticum-like skin lesions: a long-term follow-up study

BACKGROUND

Congenital haemolytic anaemia may be associated with pseudoxanthoma elasticum (PXE)-like clinical manifestations.

METHODS

The cardiovascular system of 14 homozygous and double heterozygous beta-thalassaemia patients with skin and retinal vessel alterations similar to those in genetic PXE was analysed over a period of 12 years and compared with that of 13 relatives (five sets of parents, one single parent, two thalassaemic brothers), and that of the control group composed of 16, age- and sex-matched, thalassaemic patients.

RESULTS

All patients with clinical PXE-like skin lesions exhibited, by light and electron microscopy, dermal alterations and mineralization of elastic fibres identical to those typical of inherited PXE. None of the relatives and none of the control group showed clinical or structural findings of PXE. The follow-up started in 1988. After 12 years of clinical observation, six patients showed dramatic progression of skin involvement, angioid streaks had progressed in two subjects. One patient had recurrent gastrointestinal bleeding and underwent partial stomach removal for gastric artery aneurysm, one underwent colon resection for intestinal infarct, one patient had a transitory ischaemic attack, one died after an intracranial haemorrhage, two patients died from cardiovascular disease and one from neoplasia.

CONCLUSIONS

Thalassaemic patients with PXE-like skin lesions also manifest PXE-like vessel alterations that progress with time. Considering the severe outcome of these lesions, accurate monitoring should be routinely performed on the cardiovascular system of thalassaemic patients with PXE-like skin manifestations.

Elastic tissue abnormalities resembling pseudoxanthoma elasticum in beta thalassemia and the sickling syndromes

The development of clinical and histopathologic manifestations of a diffuse elastic tissue defect, resembling inherited pseudoxanthoma elasticum (PXE), has been encountered with a notable frequency in patients with beta thalassemia, sickle cell disease, and sickle thalassemia. The PXE-like clinical syndrome, consisting of skin, ocular, and vascular manifestations, has a variable severity in these hemoglobinopathies and it is age-dependent, with a generally late onset, after the second decade of life. The defect is believed to be acquired rather than inherited and related to the consequences of the primary disease. The high prevalence of the findings implicates the elastic tissue injury as one of the main comorbid abnormalities encountered in beta thalassemia and the sickling syndromes. In these patients a number of complications, sometimes serious, has been recognized to be related to ocular and vascular elastic tissue defects. Because several organ systems are involved, each medical specialty should be aware of the phenomenon. This coexistence, on the other hand, introduces a novel pathogenetic aspect of PXE and an important research challenge.

Arterial elastorrhexis in beta-thalassaemia intermedia, sickle cell thalassaemia and hereditary spherocytosis

Arterial and stromal elastorrhexis, an elastic tissue disorder, was recently described in beta-thalassaemia major. Histopathological material from 10 patients with thalassaemia intermedia, 14 with sickle cell thalassaemia and 18 with hereditary spherocytosis was examined in order to investigate the specificity of the arteriopathy. Histological re-examination was made in a total of 42 spleens with parasplenic lymph nodes in 14 cases, 26 surgical liver biopsies and 16 gallbladders with associated regional lymph nodes. Arteriopathy, qualitatively similar to that seen in beta-thalassaemia major, was found in up to 90% of extrasplenic muscular arteries. Elastorrhexis lesions were also found in intrasplenic arteries and in stromal elastic tissue of spleens and parasplenic lymph nodes, in the absence of tissue iron overload. The arteriopathy appears in the first decade of life even in spleens of normal weight, and seems unrelated to the severity of permanent anaemia. It is suggested that patients suffering from hereditary chronic haemolytic diseases are subject to an elastic tissue disorder which is similar to hereditary pseudoxanthoma elasticum, the earliest and most frequent manifestation of which is arterial elastorrhexis of muscular extrasplenic arteries.

Cardiac involvement in thalassemia intermedia: a multicenter study

Cardiac complications in 110 patients (mean age, 32.5 ± 11.4 years) with thalassemia intermedia (TI) were studied. Sixty-seven (60.9%) of them had not been transfused or were minimally transfused (group A). The rest had started transfusions after the age of 5 years (mean, 15.1 ± 10.1 years), initially on demand and later more frequently (group B). Overall mean hemoglobin and ferritin levels were 9.1 ± 1.1 g/dL and 1657 ± 1477 ng/mL, respectively. Seventy-six healthy controls were also studied. The investigation included thorough history taking, clinical examination, electrocardiography, chest radiograph, and full resting echocardiography. Of 110 patients, 6 (5.4%) had congestive heart failure (CHF), and 9 (8.1%) had a history of acute pericarditis. Echocardiography showed pericardial thickening, with or without effusion, in 34.5% of the patients. Valvular involvement included leaflet thickening (48.1%), endocardial calcification (20.9%), and left-sided valve regurgitation (aortic, 15.4%; mitral, 47.2%). All patients had normal left ventricular contractility (fractional shortening, 0.43 ± 0.05), and high cardiac output (CO; 9.34 ± 2.28 L/min). Pulmonary hypertension (PHT), defined as Doppler peak systolic tricuspid gradient greater than 30 mm Hg, developed in 65 patients (59.1%). PHT correlated positively with age and CO and did not differ significantly between groups. Cardiac catheterization in the 6 patients with CHF revealed severe PHT, increased pulmonary resistance (PVR), and normal capillary wedge pressure. It was concluded that in patients with TI, the heart is primarily affected by PHT, which is the leading cause of CHF. High CO resulting from chronic tissue hypoxia and increased PVR are the main contributing factors. Doppler tricuspid gradient measurement should be considered, in addition to other factors, when determining the value of transfusion therapy for patients with TI.