Mitral valve prolapse in sickle cell disease: manifestation of a generalized connective tissue disorder

Pseudoxanthoma elasticum - Genetics, pathophysiology, and clinical presentation

Pseudoxanthoma elasticum (PXE) is an autosomal-recessively inherited multisystem disease. Mutations in the ABCC6-gene are causative, coding for a transmembrane transporter mainly expressed in hepatocytes, which promotes the efflux of adenosine triphosphate (ATP). This results in low levels of plasma inorganic pyrophosphate (PPi), a critical anti-mineralization factor. The clinical phenotype of PXE is characterized by the effects of elastic fiber calcification in the skin, the cardiovascular system, and the eyes. In the eyes, calcification of Bruch's membrane results in clinically visible lesions, including peau d'orange, angioid streaks, and comet tail lesions. Frequently, patients must be treated for secondary macular neovascularization. No effective therapy is available for treating the cause of PXE, but several promising approaches are emerging. Finding appropriate outcome measures remains a significant challenge for clinical trials in this slowly progressive disease. This review article provides an in-depth summary of the current understanding of PXE and its multi-systemic manifestations. The article offers a detailed overview of the ocular manifestations, including their morphological and functional consequences, as well as potential complications. Lastly, previous and future clinical trials of causative treatments for PXE are discussed.

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.

Sickle cell disease: Classification of clinical complications and approaches to preventive and therapeutic management

Sickle cell disease (SCD) is an inherited disorder of hemoglobin structure that has no established cure in adult patients. Cure has been achieved in selected children with sickle cell anemia (SCA) using allogeneic bone marrow transplantation or cord blood transplantation. SCD is essentially a triumvirate of (1) pain syndromes, (2) anemia and its sequelae and (3) organ failure, including infection. Pain, however, is the hallmark of SCD and dominates its clinical picture throughout the life of the patients. The prevalence of these complications varies with age from infancy through adult life. However, pain, infections and anemia requiring blood transfusion occur throughout the life span of affected patients. The overall medical care of patients with SCD in developed countries has improved such that their life expectancy has almost doubled since 1951. Currently, there are at least five major approaches for the general management of SCD and its complications. These include (i) symptomatic management, (ii) supportive management, (iii) preventive management, (iv) abortive management, and (v) curative therapy.

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.

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.

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.

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.

Characterization of pseudoxanthoma elasticum-like lesions in the skin of patients with beta-thalassemia

BACKGROUND

Pseudoxanthoma elasticum (PXE), an inherited disorder of unknown pathogenesis, is characterized by elastic fiber mineralization, collagen fibril alterations, and accumulation of thread material in the extracellular space. PXE-like clinical lesions have been described in patients with beta-thalassemia.

OBJECTIVE AND METHODS

Dermal lesions in these two genetic disorders were compared by light and electron microscopy and by immunocytochemistry.

RESULTS

In both disorders, elastic fiber polymorphism, fragmentation, and mineralization were structurally identical. Elastic fiber mineralization in beta-thalassemia was associated with vitronectin, bone sialoprotein, and alkaline phosphatase, similar to what was observed in inherited PXE. Furthermore, abnormalities of collagen fibrils and filament aggregates were identical in both disorders. In both inherited and beta-thalassemia-associated PXE, unrelated gene defects seem to induce cell metabolic abnormalities that lead to identical clinical and structural phenotypes.

CONCLUSION

Data indicate that patients with beta-thalassemia may undergo important alterations of connective tissues, a better understanding of which may help in preventing clinical complications.

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

Pseudoxanthoma elasticum-like lesions of the eye and skin are frequently observed in beta-thalassaemia, and there has been speculation about associated vascular lesions. This led to our study of histopathological material from thalassaemic patients. Histological re-examination was made of a series of 45 spleens and 45 surgical liver biopsies from 45 patients with beta-thalassaemia major, aged 6-25 yr and treated over the 20-yr period 1975-95. Correlations between clinical, laboratory and histological findings were demonstrated by statistical analysis. Arteriopathy characterized by fragmentation and multiple defects of the internal elastic lamina ('arterial elastorrhexis'), with deposits of iron and calcium salts, was found in the hilar arteries of the spleen with a frequency of 96%. Similar lesions were observed in the parenchymal arteries and the stromal elastic tissue ('stromal elastorrhexis') of the spleen, liver and lymph nodes. Arterial and elastic tissue alterations appear in the first decade of life and become generalized over the course of the disease, independent of the time of onset of transfusion and iron chelation therapy. Arterial elastorrhexis is the earliest and most frequent manifestation of a systemic elastic tissue disorder in beta-thalassaemia major. It appears to be an acquired pseudoxanthoma elasticum-like syndrome, related primarily to tissue hypoxia and disturbance of elastin metabolism.

Arterial calcifications in beta-thalassemia

The purpose of this study was to define the incidence of arterial calcifications in patients with beta-thalassemia. Beta-thalassemia patients have been shown to present a high prevalence of angioid streaks and skin lesions characteristic of pseudoxanthoma elasticum (PXE). Given the fact that vascular involvement in the form of arterial calcifications is also a common manifestation of PXE, the authors investigated radiographically the presence of arterial calcifications in beta-thalassemia patients. They studied 40 patients with beta-thalassemia over 30 years of age. Forty healthy, age- and sex-matched subjects were chosen as a control group. Radiographs of the tibias were performed in order to disclose arterial calcifications. The occurrence of PXE skin lesions and of angioid streaks (AS) was also investigated. Arterial calcifications were detected in the posterior tibial artery in 22 (55%) beta-thalassemia patients and in six (15%) controls (P < 0.01 for the comparison). PXE skin lesions and AS were found in eight (20%) and 21 (52%) patients respectively. A total of 34 patients (85%) had at least one of the three lesions, namely, arterial calcifications, angioid streaks, and/or PXE-like skin lesions. Stepwise logistic regression analysis did not reveal prognostic value in independent variables such as transfusions, chelation therapy, pseudoxanthoma elasticum skin lesions and/or angioid streaks, diabetes, hemoglobin, serum ferritin, and uric acid. It was concluded that arterial calcifications are common in older beta-thalassemia patients. This finding could be a manifestation of an acquired PXE syndrome associated with beta-thalassemia, and consequently, vascular events complicating PXE should be expected in these patients.

Angioid streaks in sickle-thalassemia

Angioid streaks have been described in a diverse group of diseases including hemoglobinopathies such as sickle cell anemia and beta-thalassemia. We investigated the prevalence of angioid streaks and pseudoxanthoma elasticum in the rare situation of patients who had compound heterozygous traits for hemoglobin S and beta-thalassemia. We examined 58 consecutive patients with sickle-thalassemia. Of these, 25 were men and 33 were women, and they ranged in age from 19 to 58 years (mean, 32.6 years). Angioid streaks were identified in six of 58 patients (10%), and of these three also displayed the cutaneous lesions of pseudoxanthoma elasticum, which were confirmed by skin biopsy. An expanded study on several relatives of the patients with angioid streaks failed to identify any similar cases. Statistical evaluation of the main hematologic and biochemical parameters in the patients with and without angioid streaks did not demonstrate any significant differences, except that the thalassemic component in all six patients with angioid streaks was beta(0) (that is, did not allow the synthesis of hemoglobin A). We conclude that angioid streaks and pseudoxanthoma elasticum skin lesions occur with an increased frequency in patients with sickle-thalassemia.

Pseudoxanthoma elasticum-like skin lesions and angioid streaks in beta-thalassemia

One hundred patients with homozygous or doubly heterozygous beta-thalassemia (62 with the major form and 38 with beta-thalassemia intermedia) were examined for signs of Pseudoxanthoma elasticum (PXE). Diagnostic skin lesions were found in 16 patients with either form of the basic disease. Twenty percent of all patients had angioid streaks (AS); both PXE skin lesions and AS were found in 10% of the patients; in all, 26% had either one or both of these manifestations. A positive correlation was found between the presence of one or both types of lesion and age of the patients (P = 0.032); there were no differences as regards ferritin and hematocrit levels, number of transfused units, chelation therapy, and splenic status between patients with PXE/AS findings and those without. The pathogenesis of these connective tissue manifestations at such a high frequency in beta-thalassemia is not clear; the possibilities of it's being acquired or inherited are discussed, the former being considered to be the more economical interpretation.

Pseudoxanthoma elasticum and angioid streaks in two cases of beta-thalassaemia

Two cases of beta thalassaemia with pseudoxanthoma elasticum and angioid streaks (Grönblad-Strandberg syndrome) are reported. To the best of our knowledge, this is the first report of a combination between these two genetically determined disorders. The possible theories of the pathogenesis of pseudoxanthoma elasticum and angioid streaks are discussed.

Angioid streaks in homozygous beta thalassemia

One hundred patients with homozygous beta thalassemia (62 had beta thalassemia major and 38 had beta thalassemia intermedia) were examined by ophthalmoscopy for angioid streaks. Angioid streaks were found in 20 patients from both the beta thalassemia major and beta thalassemia intermedia groups (nine and 11 patients, respectively). A positive correlation was found between age and angioid streaks (P = .0017), as was a difference in the prevalence of angioid streaks between the two forms of the disease (P = .079). Additionally, a significant correlation was noted between chelating therapy and the prevalence of angioid streaks (P = .039). However, using multivariate analysis to correct for the effects of age, the correlation of angioid streaks with the form of disease disappeared, whereas the level of significance between chelation therapy and angioid streaks was reduced (P = .05). The high frequency of angioid streaks observed in patients with beta thalassemia and the severe complications observed in one patient render a thorough ophthalmoscopic examination and follow-up of such patients necessary for both early diagnosis and possible therapeutic intervention.

Mitral valve prolapse

Mitral valve prolapse is a common mitral valve disorder manifested clinically as a midsystolic click and/or a late systolic murmur (the click-murmur syndrome) and pathologically as billowing or prolapsing mitral leaflets (the floppy valve syndrome). Not only is it one of the two most common congenital heart diseases and the most common valve disorder diagnosed in the United States, but it is also prevalent throughout the world. Mitral valve prolapse may be associated with a variety of other conditions or diseases. Diagnosis of mitral valve prolapse should be made on clinical grounds and, if necessary, supported by echocardiography. The majority of patients with mitral valve prolapse suffer no serious sequelae. However, major complications such as disabling angina-like chest pains, progressive mitral regurgitation, infective endocarditis, thromboembolism, serious arrhythmias, and sudden death may occur. Unless these serious complications occur, most of the patients with mitral valve prolapse need no treatment other than reassurance, including those with atypical chest pain or palpitation unconfirmed by objective data. Therapy with a beta-blocker for disabling chest pain and/or arrhythmias and antiplatelet therapy for cerebral embolic events may be indicated. In occasional patients with significant mitral regurgitation surgery may be necessary.

Neurologic disorders associated with mitral valve prolapse

Mitral valve prolapse has been reported to be associated with a variety of neurologic disorders, including cerebral ischemia, transient global amnesia, migraine, autonomic dysfunction, and psychiatric disease. The evidence supporting these associations and possible pathogenetic mechanisms are discussed. Some neurologic disorders may be direct complications of mitral valve prolapse, while others may occur as part of an underlying genetic defect or common link.