Pulmonary hypertension and beta-thalassemia major: report of a case, its treatment, and a review of the literature

The wide spectrum of β-thalassaemia intermedia-induced pulmonary hypertension: two case reports on the possible role of specific pulmonary arterial hypertension therapy

Pulmonary hypertension (PH) development remains a significant cardiovascular complication of haemoglobinopathies, severely affecting the morbidity and mortality of such patients. According to the 5th World Symposium on PH, PH related with chronic haemolytic anaemias is classified in group 5, mainly due to the multifactorial pathophysiology of PH in this patient population. There are no clear guidelines regarding the management of PH in patients with haemoglobinopathies; the use of specific pulmonary arterial hypertension (PAH) therapy in patients with β-thalassaemia and PH is based on data derived from other forms of PH, expert opinion and small series or case reports. The existing knowledge on the use of specific-PAH therapy in β-thalassaemia patients with PH is limited, and in most cases the diagnosis of PH is based on echocardiographic findings only. We herein report two patients with β-thalassaemia intermedia (TI) and PH, who got same initial approach but different outcome, to highlight the wide spectrum of TI-induced PH, the importance of optimal disease-directed therapy and the possible role of specific-PAH therapy. We also emphasize the central role of right heart catheterization in the diagnosis and follow-up of PH, since this information does facilitate the suitable use or withdrawal of specific PAH drugs in these patients.

Red Blood Cell Exchange in a Patient With Extramedullary Hematopoiesis and Cor Pulmonale Secondary to Beta Thalassemia

Rationale: Beta thalassemia is a congenital defect in the production of the beta globin chain. Patients with beta thalassemia major will have higher levels of hemoglobin F (HbF), which is suboptimal in releasing oxygen to tissue. Herein, we describe the use of red blood cell (RBC) exchange transfusion, a therapy typically used in sickle cell patients, in the management of a patient with beta thalassemia with extensive extramedullary hematopoiesis and elevated levels of HbF.

Patient concerns: A 34-year-old male of mixed African American and Southeast Asian descent with a known history of beta thalassemia major presented with progressive dyspnea on exertion with marked fatigue.

Diagnoses: The patient was transferred to our facility for management of acute hypoxemic, hypercapnic respiratory failure associated with cor pulmonale.

Interventions: The patient was initially managed with non-invasive positive pressure support ventilation (NIPPV) and intravenous diuresis. Hydroxyurea and epoprostenol nebulization were added to his treatment regimen; however, he progressively became more unstable, necessitating inotropic support. With extramedullary hematopoiesis leading to mass-like effect on critical organs and very high HbF (96%) thought to contribute to his presentation, red blood cell exchange transfusion was initiated once the blood pressure stabilized.

Outcomes: The patient clinically improved, and was discharged home within a week on supplemental oxygen by nasal cannula and long-term red blood cell exchange.

Lessons: We postulated that significantly elevated HbF contributed to the patient’s chronic hypoxia and subsequent respiratory complications. Based on the patient's clinical improvement following the intervention, we believe that RBC exchange transfusion could be considered in the management of beta thalassemia patients with significantly elevated levels of HbF.

How I treat hypoxia in adults with hemoglobinopathies and hemolytic disorders

Hemoglobinopathies are caused by genetic mutations that result in abnormal hemoglobin molecules, resulting in hemolytic anemia. Chronic complications involving the lung parenchyma, vasculature, and cardiac function in hemoglobinopathies result in impaired gas exchange, resulting in tissue hypoxia. Hypoxia is defined as the deficiency in the amount of oxygen reaching the tissues of the body and is prevalent in patients with hemoglobinopathies, and its cause is often multifactorial. Chronic hypoxia in hemoglobinopathies is often a sign of disease severity and is associated with increased morbidity and mortality. Therefore, a thorough understanding of the pathophysiology of hypoxia in these disease processes is important in order to appropriately treat the underlying cause and prevent complications. In this article, we discuss management of hypoxia based on three different cases: sickle cell disease, β-thalassemia, and hereditary spherocytosis. These cases are used to review the current understanding of the disease pathophysiology, demonstrate the importance of a thorough clinical history and physical examination, explore diagnostic pathways, and review the current management.

Pulmonary hypertension associated with thalassemia syndromes

Chronic hemolytic anemia has increasingly been identified as an important risk factor for the development of pulmonary hypertension (PH). Within the thalassemia syndromes, there are multiple mechanisms, both distinct and overlapping, by which PH develops and that differ among β-thalassemia major or intermedia patients. PH in β-thalassemia major correlates with the severity of hemolysis, yet in patients whose disease is well treated with chronic transfusion therapy, the development of PH can be related to cardiac dysfunction and the subsequent toxic effects of iron overload rather than hemolysis. β-Thalassemia intermedia, on the other hand, has a higher incidence of PH owing to the low level of hemolysis that exists over years without the requirement for frequent transfusions, while splenectomy is shown to play an important role in both types. Standard therapies such as chronic transfusion have been shown to mitigate PH, and appropriate chelation therapy can avoid the toxic effects of iron overload, yet is not indicated in many patients. Limited evidence exists for the use of pulmonary vasodilators or other therapies, such as l-carnitine, to treat PH associated with thalassemia. Here, we review the most recent findings regarding the pathogenic mechanisms, epidemiology, presentation, diagnosis, and treatment of PH in thalassemia syndromes.

Pulmonary hypertension in well-transfused thalassemia major patients

The risk for pulmonary hypertension (PH) in thalassemia major (TM) patients remains controversial. We report echocardiography results from 60 TM patients: we evaluated the association between tricuspid regurgitation velocities (TRV), iron stores, and serologic markers of hemolysis and arginine dysregulation. Patients were enrolled from August 2004 until May 2009. All parameters were inversely weighted by the number of exams. TRV was comparable between sexes and it was uncorrelated with age. At the first exam, TR velocities at the upper limits of normal (2.5-2.7m/s) were observed in 8 patients. An abnormal TRV (2.9m/s) was found in 1 patient. Borderline increases in TRV were associated with a reduced global arginine bioavailability (R=-0.399 P=0.005), increased anemia (hemoglobin: R=-0.219 P=0.0461), cardiac index (R=0.223 P=0.0481), and diastolic dysfunction (E/A: R=0.289 P=0.0088; E/E': R=0.223 P=0.0453), but not hemolysis, iron overload and systolic function evaluated by Magnetic Resonance Imaging, and splenectomy. Well-transfused TM patients have a lower risk for PH than thalassemia intermedia patients. However, they do have vascular stressors that raise their lifetime PH risk to levels higher than for the general population. Consequently, we support recommendations for annual echocardiographic screening and cardiac catheterization for persistent TRV above 3m/s.

Pulmonary arterial hypertension in a patient with β-thalassemia intermedia and reversal with infusion epoprostenol then transition to oral calcium channel blocker therapy: review of literature

Pulmonary arterial hypertension (PAH) is a potentially life-threatening complication of thalassemia. A sexagenarian with β-thalassemia intermedia presented with new-onset dyspnea and syncope. Right heart catheterization confirmed severe PAH. Her functional class IV symptoms and severely elevated mean pulmonary artery pressure prompted the initiation of continuous epoprostenol therapy. Clinical follow-up documented significant improvement in functional class, 6-minute walk distance, and right ventricular size and function as well as pulmonary arterial pressure on echocardiogram. At the patient's request, epoprostenol was down-titrated and eventually discontinued. The patient was then safely transitioned to nifedipine therapy after verification of vasoresponsiveness.

Pulmonary hypertension associated with chronic hemolytic anemia and other blood disorders

Pulmonary hypertension (PH) has emerged as a major complication of several hematologic disorders, including hemoglobinopathies, red cell membrane disorders, chronic myeloproliferative disorders, and splenectomy. With the exception of sickle cell disease, there are a limited number of studies systematically evaluating the prevalence of PH using the gold standard right heart catheterization in these disorders. The cause of the PH in patients with hematologic disorders is multifactorial, and a thorough diagnostic evaluation is essential. More importantly, there are virtually no high-quality data on the safety and efficacy of PH-targeted therapy in this patient population.

Pulmonary hypertension in β thalassaemia

Pulmonary hypertension is one of the leading causes of morbidity and mortality in patients with haemolytic disorders and is a frequent finding in echocardiographic screening of patients with β thalassaemia. Substantial progress has been made in understanding of the multifactorial pathophysiology of pulmonary hypertension in β thalassaemia. Haemolysis, reduced nitric oxide bioavailability, iron overload, and hypercoagulopathy are among the main pathogenetic mechanisms. Various disease-directed therapeutic methods, such as transfusion, chelation, and splenectomy, have important roles in the development of pulmonary hypertension in β thalassaemia. Studies investigating the prevalence of pulmonary hypertension in β thalassaemia are mostly based on echocardiographic findings, and are thus limited by the scarcity of information derived from right heart catheterisation. Invasive pulmonary haemodynamic data are needed to clarify the true prevalence of pulmonary hypertension in β thalassaemia, to better understand the underlying pathophysiology and risk factors, and to define the optimum therapy for this devastating complication.

Sildenafil therapy in thalassemia patients with Doppler-defined risk of pulmonary hypertension

Pulmonary hypertension is a common but often overlooked complication associated with thalassemia syndromes. There are limited data on the safety and efficacy of selective pulmonary vasodilators in this at-risk population. We, therefore, designed a 12-week, open-label, phase 1/2, pilot-scale, proof-of-principle trial of sildenafil therapy in 10 patients with β-thalassemia and at increased risk of pulmonary hypertension based on an elevated tricuspid regurgitant jet velocity >2.5 m/s on Doppler-echocardiography. Variables compared at baseline and after 12 weeks of sildenafil treatment included Doppler-echocardiographic parameters, 6-minute walked distance, Borg Dyspnea Score, New York Heart Association functional class, pulmonary function, and laboratory parameters. Treatment with sildenafil resulted in a significant decrease in tricuspid regurgitant jet velocity by 13.3% (3.0±0.7 versus 2.6±0.5 m/s, P=0.04), improved left ventricular end systolic/diastolic volume, and a trend towards a improved New York Heart Association functional class. No significant change in 6-minute walked distance was noted. Sildenafil was well tolerated, although minor expected adverse events were commonly reported. The total dose of sildenafil (mg) was strongly correlated with percent change in nitric oxide metabolite concentration in the plasma (ρ=0.80, P=0.01). There were also significant increases in plasma and erythrocyte arginine concentrations. Our study suggests that sildenafil is safe and may improve pulmonary hemodynamics in patients at risk of pulmonary hypertension; however, it was not demonstrated to improve the distance walked in 6 minutes. Clinical trials are needed to identify the best treatment strategy for pulmonary hypertension in patients with β-thalassemia. (clinicaltrials.gov identifier: NCT00872170).

Frequency of pulmonary hypertension in asymptomatic β-thalassemia major patients and the role of physiological parameters in evaluation

In this study, the authors aimed to evaluate the frequency of pulmonary hypertension (PHT) in asymptomatic thalassemia major (TM) patients, and to investigate the impact of pulmonary function test (PFT) and CO diffusion results on the evaluation of pulmonary hypertension. Data from 50 asymptomatic patients with TM over age 10 were evaluated. Pulmonary hypertension was diagnosed in 10 patients (20%). High tricuspid regurgitant jet velocity was found in 14% of adults and in 25% of children. Pulmonary function test including CO diffusion testing results were not different between the TM patients with or without pulmonary hypertension. In conclusion, PHT was frequent among TM patients even they were asymptomatic and although PFT results has shown lack of association, it should be investigated in larger population.

Pulmonary hypertension in thalassemia

Pulmonary hypertension (PH) is common in thalassemia and contributes to mortality. Advancing age and a history of splenectomy are major risk factors in this population. The etiology of PH is multifactorial, involving a complex interaction of platelets, the coagulation system, erythrocytes, and endothelial cells along with inflammatory and vascular mediators. The long-term effect of splenectomy, red cell membrane pathology, coagulation abnormalities, low nitric oxide (NO) bioavailability, excess arginase activity, platelet activation, oxidative stress, iron overload, and chronic hemolysis play a role. The process of hemolysis disables the arginine-NO pathway through the simultaneous release of erythrocyte arginase and cell-free hemoglobin. Both NO and its obligate substrate arginine are rapidly consumed. The biological consequences of hemolysis on NO bioavailability ultimately translate into the clinical manifestations of PH. Guidelines for the management of PH in thalassemia have not yet been established; however, clinical trials are ongoing in an effort to guide future therapy.

N-terminal natriuretic peptide and ventilation-perfusion lung scan in sickle cell disease and thalassemia patients with pulmonary hypertension

The aim of this study was to determine the prevalence of pulmonary hypertension (PH) in sickle cell disease and thalassemia patients in relation to clinical and laboratory parameters of hemolysis and hemosidersosis, as well as plasma N-terminal pro-brain natriuretic peptide (NT-pro-BNP). The study also aimed to define the role of thromboembolic pulmonary artery (PA) obstruction in its etiology. Forty sickle cell disease and 30 thalassemia patients [15 beta-thalassemia major (beta-TM) and 15 beta-thalassemia intermedia (beta-TI)] were screened for PH defined as tricuspid regurgitant velocity (TRV) >2.5 m/sec and evaluated for PA obstruction using ventilation-perfusion lung scan (V/Q), together with measurement of their plasma levels of NT-pro-BNP. Patients were prospectively followed up for a mean of 18 +/- 6.1 months. The prevalence of PH was 37.5, 40.0 and 26.7% in sickle cell disease, beta-TI and beta-TM patients, respectively. Pulmonary hypertension patients were older, had longer disease duration, higher serum ferritin, serum lactate dehydrogenase (LDH) and NT-pro-BNP with lower hemoglobin (Hb) levels compared to patients without PH. N-terminal pro-BNP was positively correlated with duration of illness, TRV, LDH, serum ferritin, and negatively correlated with Hb levels. The strongest predictor for TRV was serum ferritin followed by the NT-pro-BNP level. Forty-six-point-seven percent of sickle cell disease patients with PH had either high or intermediate probability V/Q scan results compared to 10% of thalassemic patients with PH who had high probability V/Q scan results. Pulmonary hypertension is highly prevalent in young sickle cell disease and thalassemia patients, where elevated serum ferritin and NT-pro-BNP are the main indicators.

Delayed adverse vascular events after splenectomy in hereditary spherocytosis

BACKGROUND

It is probable that the variety and frequency of delayed adverse vascular events after splenectomy are underappreciated. Splenectomy is performed for a wide variety of conditions, and delayed postsplenectomy hazards are not often studied.

OBJECTIVE

To estimate the relative risk of adverse vascular events in members of hereditary spherocytosis families who have or have not had a splenectomy.

METHODS

Members of families in which hereditary spherocytosis exists were systematically questioned about adverse vascular events.

RESULTS

The cumulative incidence of arterial and venous events at age 70 years was greater in persons who had undergone a splenectomy for spherocytosis (arterial, 22% females, 32% males; venous, 20% females, 19% males) than in affected persons who did not undergo splenectomy (arterial, 3% females, 2% males; venous, 6% females, 4% males) or non-affected family members (arterial, 10% females, 17% males; venous, 4% females, 12% males). Affected subjects who undergo splenectomy are at greatly increased risk of arterial events as compared to affected subjects who do not undergo splenectomy [arterial, hazard ratio (HR) 7.2, 95% confidence interval (CI) 2.8-17.2; venous, HR 3.3, 95% CI 1.1-9.8].

CONCLUSION

There is a significant, long-lasting, increased risk of adverse arterial and venous thromboembolic events after splenectomy performed for hereditary spherocytosis. A review of the literature indicates that this is also true when splenectomy is performed for several other indications.