Right ventricular and pulmonary function in sickle cell disease patients with pulmonary hypertension

[Decreased Heart Rate Variability in Sickle Cell Anemia as Effect of Pulmonary Arterial Hypertension]

Decreased heart rate variability (HRV) is associated with increased mortality risk in various diseases. The objective of this investigation:to study HRV in patients with sickle cell anemia (SCA) and to assess the effect of pulmonary arterial hypertension (PAH) on HRV in these patients. Materials and methods. HRV registration and Doppler echocardiographic assessment of systolic pulmonary arterial pressure (PAP) was carried out in 61 stable patients with SCA and 24 healthy subjects. Results. Low frequency power (LFP) and high frequency power (HFP) were decreased in SCA patients compared to healthy subjects. Among SCA patients, PAH patients had lower  LFP and HFP than patients without PAH. In SCA patients, systolic PAP showed significant negative correlation with LFP and HFP. Conclusion. HRV is significantly decreased in SCA patients, especially in those with PAH. HRV may be particularly useful in early detection of PAH patients who may have worse prognosis and higher mortality risk.

Cardiac Structural and Functional Changes Evaluated by Transthoracic and Tissue Doppler Echocardiography in Adult Patients with Sickle Cell Disease

One of the most common genetic blood disorders, resulting from inherited red blood cell disorders, is sickle cell disease (SCD) which is responsible for high death in adult patients with left ventricular diastolic dysfunction and pulmonary hypertension. Tissue Doppler Echocardiography (TDE) and transthoracic echocardiography (TTE) are two useful tools to assess the risk of SCD. The present study was conducted to evaluate the cardiac functions and structure using TDE and TTE among adult patients suffering from sickle cell anemia compare to normal samples.

Lung function in sickle cell disease

Although some of the most severe complications of Sickle Cell Disease (SCD) tend to be acute and severe (e.g. acute chest syndrome, stroke etc.), the chronic ones can be equally debilitating. Prominent among them is the effect that the disease has on lung growth and function. For many years the traditional teaching has been that SCD is associated with the development of a restrictive lung defect. However, there is increasing evidence that this is not a universal finding and that at least during childhood and adolescence, the majority of the patients have a normal or obstructive pattern of lung function. The following article reviews the current knowledge on the effects of SCD on lung growth and function. Special emphasis is given to the controversies among the published articles in the literature and discusses possible causes for these discrepancies.

Somatic growth and lung function in sickle cell disease

Somatic growth is a key indicator of overall health and well-being with important prognostic implications in the management of chronic disease. Worldwide studies of growth in children and adults with SCD have predominantly shown delayed growth (especially in terms of body weight) that is gradual and progressive in nature. However, more recent studies have shown that a substantial number of patients with SCD have normal weight gain whereas some are even obese. Height in patients with SCD is not universally affected even among those with suboptimal weight gain, whereas some achieve the same or greater height than healthy controls. The relationship between somatic growth and lung function in SCD is not yet clearly defined. As a group, patients with SCD tend to have lower lung volumes compared with healthy controls. These findings are similar across the age spectrum and across ethnic/racial lines regardless of the differences in body weight. Several mechanisms and risk factors have been proposed to explain these findings. These include malnutrition, racial differences and socioeconomic status. In addition, there are structural changes of the thorax (specifically the anterio-posterior chest diameter and anterio-posterior to lateral chest ratio) specific to sickle cell disease, that potentially interfere with normal lung growth. Although, caloric and protein intake have been shown to improve both height and weight, the composition of an optimal diet remains unclear. The following article reviews the current knowledge and controversies regarding somatic growth and its relationship with lung function in sickle cell disease (SCD) as well as the role of specific deficiencies of certain micronutrients.

[Cardiopulmonary complications in sickle cell anemia]

Sickle cell anemia, considered the most prevalent genetic disease among African Americans, is a disease with autosomal recessive inheritance pattern, characterized by the production of hemoglobin S. This abnormal protein polymerizes and facilitates the formation of fibrillar aggregates that alters the erythrocyte morphology. The stiffness of the red blood cells hinders the adequate transit across microcirculation, leading to hemolysis and increased blood viscosity, which ease thrombogenesis and vascular occlusion, resulting in tissue ischemia and microinfarcts. This disease has a high rate of morbidity and mortality, especially in the first three years of life, when a rapid diagnosis and appropriate treatment are essential. Cardiovascular complications such as heart failure and pulmonary hypertension may develop independently, and each one contributes to increased mortality, being the combination of both risk factors, an important aggravating factor for prognosis and a determinant indicator of mortality.

Left ventricular myocardial performance assessed by 2-dimensional speckle tracking echocardiography in patients with sickle cell crisis

BACKGROUND

The status of left ventricle in sickle cell anemia presenting in sickle crisis and follow up has been minimally studied in past. To determine the left ventricular (LV) myocardial performance in these patients, we performed the study to assess two dimensional strains imaging which allowed a rapid and an accurate analysis of global and regional LV myocardial performance in longitudinal, radial, and circumferential directions.

METHODS

In this prospective study, 2-dimensional echocardiography (2DE) images of the LV were obtained in 52 subjects which included 32 patients (23 ± 8yrs, 16 male) with homozygous sickle cell anemia (SCA) in sickle cell crisis and 20 healthy controls (23 ± 5 yrs, 11 male) using apical 4-chamber and parasternal short-axis at the basal, mid, and apical levels. Of these 32 patients, 2DE was performed again in 18 patients in follow up (8 months ± 5 days). Longitudinal, circumferential and radial strains (LS, CS and RS respectively) were quantified and compared in an 18-segment model using a novel speckle tracking system (2D Cardiac Performance Analysis, TomTec Imaging System, Munich, Germany).

RESULTS

There was no significant difference in LV ejection fraction between both the groups (59.32 ± 12.6 vs. 52.3 ± 7.9; p-value > 0.05). In comparison with normal controls and follow up of sickle cell patients, peak LS was significantly attenuated in the subendocardial and subepicardial regions during sickle cell crisis (p < 0.05). However, a significant reduction in circumferential strain was evident only in subepicardial region (p < 0.001). Also patients in sickle cell crisis showed significantly higher radial strain parameters than controls (p < 0.001).

CONCLUSION

Patients with SCA presenting in sickle cell crisis have reduced longitudinal shortening. LV myocardial performance remains unaltered due to relatively preserved circumferential shortening and increased radial thickening.

Ventricular structure and function in children with sickle cell disease using conventional and tissue Doppler echocardiography

Conventional 2-dimensional, M-mode, and spectral Doppler echocardiographic techniques have documented abnormal ventricular function in adults with sickle cell disease (SCD), but assessments in children are conflicting. Tissue Doppler echocardiography (TDE) provides additional information about myocardial function. Two-dimensional, M-mode, tricuspid regurgitation jet velocity (TRJV) data, and tissue Doppler echocardiographically derived myocardial velocity measurements of left ventricular (LV) and right ventricular function were taken from children with SCD compared to those of similar healthy historical controls and correlated with clinical characteristics and hemoglobin levels. Compared to 55 controls, 54 children with SCD (mean age 14.2 years, range 6 to 21) had a larger left ventricle, greater LV mass, and higher LV fractional shortening; 30% had increased pulmonary artery pressure (TRJV ≥2.5 m/s). Conventional echocardiographic measurements of LV systolic function and spectral Doppler measurements of LV and right ventricular diastolic function were essentially normal, but TDE indicated that 31% of SCD children had evidence of LV diastolic dysfunction (peak early diastolic velocity of LV inflow Doppler/peak early diastolic velocity at lateral mitral valve annulus >8), a finding that correlated with lower hemoglobin levels. Although decreasing hemoglobin levels in children with SCD correlated with LV hypertrophy, LV dilation, and LV diastolic dysfunction, long-term transfusion or hydroxyurea therapy did not affect these measurements. In conclusion, 1/3 of children with SCD had tissue Doppler echocardiographic evidence of LV diastolic dysfunction, which was correlated with hemoglobin levels. Adding serial assessments of ventricular function with TDE to conventional echocardiography may detect early cardiac changes, especially in children with severe anemia.

The impact of recurrent acute chest syndrome on the lung function of young adults with sickle cell disease

The aim of this study was to assess the impact of recurrent acute chest syndrome (ACS) episodes on the lung function of young adults with sickle cell disease (SCD). Our prospective study included 80 SCD adults [26 with recurrent acute chest syndrome (ACS)] and 80 ethnically matched controls aged between 18 and 28 years. Lung function (spirometry and lung volumes) was measured and the results were expressed as the percentage predicted for height. Bronchial hyperresponsiveness (BHR) was assessed by the response to either a bronchodilator or an exercise challenge. The adults with recurrent ACS (two or more ACS episodes) had lower median forced vital capacity (74 vs. 83%, p = 0.03), forced expiratory volume in 1 s (79 vs. 90%, p < 0.03), and total lung capacity (69 vs. 81%, p = 0.04) than SCD adults who had one or no ACS episodes. The greater the number of ACS episodes, the greater the reduction in lung function (p = 0.001). The adults with SCD had lower median forced vital capacity (81 vs. 106%), forced expiratory volume in 1 s (85 vs. 107%), and total lung capacity (80 vs. 87%) than the controls (p < 0.001). Similar numbers in each group had BHR (p = 0.2). The prevalence of restrictive ventilatory defect in the patients with SCD was almost double that of the controls (p = 0.004). Young adults with SCD have worse lung function than ethnically matched controls, particularly if they have suffered recurrent ACS episodes.

Assessment of cardiac functions in sickle cell anemia with Doppler myocardial performance index

BACKGROUND

The purpose of this study was to evaluate left and right ventricular functions by using the Doppler myocardial performance index (MPI), in children with sickle cell anemia (SCA).

METHODS

We examined 32 patients with SCA and 30 age-matched healthy children. Echocardiography and Doppler examinations were completed for each of the subjects. MPI was calculated from the Doppler tracings.

RESULTS

Compared with controls, left ventricle (LV) end-diastolic diameter, end-systolic diameter, early-diastolic mitral flow velocity and late-diastolic mitral flow velocity were significantly higher in the patients with SCA. Although, the LV ejection fractions were in the normal ranges in patients and controls, both LV and right ventricle (RV) MPI were significantly higher in patients than those in normal children.

CONCLUSION

MPI may be a useful noninvasive and sensitive tool for assessing the sub-clinical cardiac LV and RV dysfunctions in patients with SCA.

Prospective echocardiography assessment of pulmonary hypertension and its potential etiologies in children with sickle cell disease

Pulmonary hypertension (PH) is associated with adverse outcomes in adults with sickle-cell disease (SCD), but its importance in children is less clear. The aim of this study was to define the incidence and causes of PH in pediatric patients with SCD. Children with SCD (n = 310) and matched controls (n = 54) were prospectively enrolled under basal conditions. Participants underwent echocardiography, pulse oximetry, 6-minute walk tests, and hematologic testing. Echocardiographic measures were compared between patients with SCD and control subjects before and after adjusting for hemoglobin. Correlations of echocardiographic and clinical parameters were determined. Tricuspid regurgitation velocity (TRV) was elevated compared to controls (2.28 vs 2.10 m/s, p <0.0001). Increased TRV was associated with left ventricular diastolic diameter, hemoglobin, and estimated left atrial pressure. TRV remained elevated when controlling for left ventricular diameter and left atrial pressure. Echocardiographically derived pulmonary resistance was not significantly different between patients with SCD and controls, although it was elevated in the SCD subgroup with elevated TRV. When controlling for hemoglobin, TRV was no longer statistically different, but pulmonary insufficiency velocity, septal wall thickness, and estimated pulmonary resistance were statistically higher. TRV, pulmonary insufficiency end-diastolic velocity, and markers of increased cardiac output were correlated with indicators of adverse functional status, including history of acute chest syndrome, stroke, transfusions, and 6-minute walk distance. In conclusion, children with SCD had mildly increased TRV that was correlated with increased cardiac output and left ventricular filling pressures. Hemoglobin-adjusted analysis also suggested a contribution of primary vascular changes.

Echocardiographic findings in patients with sickle cell disease

Pulmonary hypertension is a complication of sickle cell disease that is associated with increased mortality. Whether this complication is associated with hemolysis has been questioned. Systolic pulmonary artery blood pressure can be estimated from echocardiography-determined tricuspid regurgitation velocity (TRV). A velocity of 2.5 m/s or higher suggests possible pulmonary hypertension. A retrospective review of hospital records from adult patients with sickle cell disease undergoing echocardiography in 2006 and 2007 was performed at a tertiary level hospital. Echocardiographic, demographic, and clinical laboratory data were collected. Echocardiographic results were available for 105 adult sickle cell patients. Of these, 62 (59%) had a TRV ≥2.5 m/s and 24 (22.8%) had a TRV ≥3.0 m/s. Mitral valve regurgitation was observed in 44% and left ventricular abnormalities (defined by either hypertrophy or dilation) in 28% of cases. Elevated TRV had independent and significant associations with greater age, higher serum lactate dehydrogenase (LDH) concentration, and lower hemoglobin concentration. We confirmed that elevated TRV is common among hospital-based adults with sickle cell disease. Significant, independent associations were found with both elevated LDH concentration and degree of anemia, suggesting that hemolytic and other mechanisms contribute to pulmonary hypertension in patients with sickle cell disease.

Impact of right ventricular contrast attenuation on the accuracy of right ventricular function analysis at cardiac multi-detector-row CT

PURPOSE

To investigate the impact of right ventricle (RV) contrast attenuation on the accuracy of RV function analysis at cardiac CT performed for coronary imaging.

MATERIALS AND METHODS

We analyzed multi-phase cardiac dual-source CT studies of 40 consecutive patients (mean age 60.9+/-12.3 years; 13 women) with normal valve function. Function analyses of both the right and left ventricle (RV and LV) were performed using dedicated post processing software and stroke volumes (SV) were computed for each ventricle. The accuracy of the RV-SV measurements was determined based upon comparison to LV-SV measurement. The level of contrast attenuation of the RV was recorded at three separate regions of interest-below the pulmonary valve, mid-ventricular, and inferior RV. The accuracy of RV function assessment was correlated with the level of attenuation using regression analyses.

RESULTS

There was a statistically significant correlation between the accuracy of RV function assessment and the level of RV attenuation in the inferior RV (adjusted R(2)=73.1%, p<0.0001). When compared to LV-SV measurements, in studies with low RV attenuation (<175 HUs, n=19) the mean deviation of RV-SV from LV-SV was 29.0+/-10.8 ml (42.1+/-13.9%). In studies with high RV attenuation (> or =175 HUs, n=21) the mean deviation of RV-SV from LV-SV was significantly lower 6.9+/-10.5 ml (9.9+/-16.0%).

CONCLUSION

The accuracy of RV function analysis is dependent on the level of contrast medium attenuation achieved in the inferior RV. There should be at least intermediate attenuation (>175 HUs) to enable accurate functional analysis. At low attenuation levels RV function parameters are prone to underestimation.

Cardiopulmonary imaging, functional and laboratory studies in sickle cell disease associated pulmonary hypertension

Pulmonary hypertension (PHT) occurs in approximately 30% of adults with sickle cell disease (SCD) and is an independent risk factor for early death. In this study, we aimed to determine the value of general laboratory testing, plain chest radiography, electrocardiography (ECG), high-resolution computer tomography (HRCT) of the thorax, pulmonary function testing, and plasma N-terminal brain natriuretic peptide (NT-proBNP) and brain natriuretic peptide (BNP) in patients with SCD-related PHT. A cohort of 85 ambulatory sickle cell patients were prospectively screened for PHT with echocardiography (defined as a tricuspid regurgitation flow velocity of > or =2.5 m/sec). All patients were systematically evaluated by the aforementioned diagnostic tests comparing patients with and without PHT. The prevalence of PHT was 41% in HbSS/HbSbeta(0)-thalassemia patients and 13% in HbSC/HbSbeta(+)-thalassemia patients. No statistically significant differences were detected in ECG, chest radiography, HRCT, and pulmonary function testing between patients with and without PHT. The degree of anemia and renal dysfunction, but not the presence of PHT, were the most important determinants of plasma (NT-pro)BNP levels. The performed imaging and functional studies do not seem to be of value in identifying etiological conditions (such as airflow obstruction or parenchymal lung disease) nor do they offer clues to the presence of mild PHT in SCD.

Pulmonary complications of sickle cell disease in children

PURPOSE OF REVIEW

Sickle cell disease is one of the most prevalent genetic diseases, affecting 1 in 600 African-Americans. The lung is one of the major organs affected in sickle cell disease and the pulmonary complications of sickle cell disease result in significant morbidity and mortality in children.

RECENT FINDINGS

Recent literature has provided evidence supporting the strong association between asthma and airway hyperreactivity and sickle cell disease, as well as a link with acute chest syndrome and vaso-occlusive crisis. Additionally, children with sickle cell disease who have acute chest syndrome episodes have worse pulmonary function than those who have not experienced acute chest syndrome episodes. An increasing amount of literature highlights the link between pulmonary hypertension and sickle cell disease, and multiple mechanisms have been invoked to explain why patients with sickle cell disease are prone to the development of pulmonary hypertension. Previous and current studies have also highlighted the manifestations of sleep disordered breathing in children with sickle cell disease.

SUMMARY

The pulmonary complications of sickle cell disease include airway hyperreactivity, acute chest syndrome, chronic sickle lung disease, pulmonary hypertension, and sleep disordered breathing. Further understanding of the interrelationships between these disorders will lead to improved therapies.

Standard measures of right ventricular function assessment in adult patients with acute sickle cell crises

Chronic sickle cell (SC) disease is known to cause pulmonary hypertension (PH) which eventually affects right as well as left ventricular function. However, the acute effects of SC crisis on right ventricular (RV) function in adults have not been well described. Our echocardiography database was queried for patients followed in the outpatient hematology clinic, who were admitted with SC crises, and had an inpatient echocardiogram. Comparisons of RV fractional area change (RVFAC) and tricuspid annular peak systolic excursion (TAPSE) were then made to a group of healthy patients and a group with mild PH. TAPSE was normal in patients with SC disease (3.05+/-0.56). However, the SC patients had significantly larger RV's compared to controls and mild PH patients (31.33+/-7.23 cm(2) vs. 19.07+/-4.49 cm(2) and 21.51+/-6.07 cm(2), respectively, P<0.0001). RVFAC was reduced in SC patients, and was comparable to patients with mild PH (46+/-9% vs. 49 +/-14%, P=0.4). We found no correlation between hemoglobin level (8.1+/-2.5 g) and RVFAC, TAPSE, or PH severity. We found that adult patients admitted with SC crises have frequent dilatation of the RV with an abnormal reduction in RVFAC, despite normal TAPSE values. Therefore, caution should be exercised in using TAPSE to estimate RV function in this patient population.

Increased QT dispersion in sickle cell disease: effect of pulmonary hypertension

BACKGROUND

QT dispersion has been proposed to be a predictor of adverse outcomes in a variety of cardiac disease states. The objective of this study was to examine QT dispersion in patients with sickle cell disease (SCD) and to assess the effect of pulmonary hypertension (PHT) on QT dispersion.

METHODS

We performed Doppler echocardiographic assessments of pulmonary artery systolic pressure in 73 (mean age 18.5 +/- 8.0 years) steady-state SCD patients and 25 (mean age 19.6 +/- 7.2 years) healthy subjects. Resting 12-lead electrocardiogram was recorded and QT dispersion was calculated as the difference between maximum and minimum QT intervals. Bazett's formula was used to obtain a rate-corrected value of the QT interval (QTc).

RESULTS

Maximum QTc, minimum QTc and QTc dispersion were significantly increased in SCD patients compared to the control subjects (p < 0.0001, p < 0.05, p < 0.0001, respectively). Among SCD patients, patients with PHT had higher maximum QTc and QTc dispersion than patients without PHT (p < 0.0001). However, minimum QTc showed no significant differences between the two patient groups.

CONCLUSION

QTc dispersion is significantly increased in SCD patients, especially those with PHT indicating regional inhomogeneity of ventricular repolarization.