Cardiac performance in children with homozygous sickle cell disease

Coronary artery dilation and left ventricular hypertrophy do not predict morbidity in children with sickle cell disease

BACKGROUND

Little is known about the clinical significance of coronary artery dilation (CAD) and left ventricular hypertrophy (LVH) in patients with sickle cell disease (SCD).

PROCEDURE

In a retrospective cohort, we studied the prevalence of CAD and LVH in 101 children with SCD in comparison to 93 healthy African-American patients without SCD. Hospital days, number of admissions, and intensive care unit admission after the echocardiogram were assessed as measures of morbidity.

RESULTS

Multivariable analysis of echocardiographic measures of LVH and CAD did not predict subsequent intensive care unit admission, hospital days/year or number of hospital admissions/year during a median follow-up time of 6.1 years. LVH as measured by left ventricular mass index was present in 46% of children with SCD and was inversely related to age (P = 0.0004). Height-indexed dimensions in children with SCD demonstrated that the prevalence of dilation was 49% for the left main coronary artery (LMCA), 29% for the left anterior descending (LAD), and 6% for the right coronary artery (RCA). LMCA dilation was related to relative wall thickness (P = 0.006), inversely to age (P < 0.0006) and weakly to disease severity as determined by hemoglobin (P = 0.03). CAD and LVH were not related to a clinical history of vaso-occlusive pain episode, acute chest syndrome, or cerebrovascular accident.

CONCLUSION

LVH and CAD are common findings in children with SCD; however, they are not associated with need for subsequent hospital or intensive care unit admission.

Left ventricular systolic function in sickle cell anemia: a meta-analysis

BACKGROUND

We sought to evaluate whether patients with sickle cell anemia (SCA) have left ventricular (LV) systolic dysfunction.

METHODS AND RESULTS

We conducted a Medline, Embase, Ebscohost, and Google scholar literature search articles published before April 2010. All studies that compared any measure of LV function (eg, ejection fraction [EF], fractional shortening [FS], or cardiac index [CI]) between normal control subjects and SCA (hemoglobin SS) patients were included. Among 57 studies that qualified for review, 19 studies including 841 SCA patients and 554 control subjects met the inclusion criteria. There were no significant differences in either LVEF (Hedge g = 0.15; 95% confidence interval -0.84 to 1.14; P = .76) or FS (P = .28) between SCA patients and control subjects. CI was significantly higher (P < .001) and LV end-systolic stress-volume index (load independent) was significantly lower (P < .001) in SCA patients. All LV systolic measures inversely correlated with age (all P < .001). LV end-systolic and -diastolic dimensions were significantly higher in SCA patients and increased with age.

CONCLUSIONS

SCA patients have similar load-dependent but lower load-independent measures of LV systolic function than control subjects. SCA is associated with LV dilation. LV structural and functional abnormalities appear to be age dependent with progressive LV dilation and impairment over time.

The PhysioFlow thoracic impedancemeter is not valid for the measurements of cardiac hemodynamic parameters in chronic anemic patients

The aim of the present study was to test the validity of the transthoracic electrical bioimpedance method PhysioFlow® to measure stroke volume in patients with chronic anemia. Stroke volume index (SVI), as well as cardiac index (CI) obtained by transthoracic electrical bioimpedance method and doppler echocardiography were compared in healthy subjects (n = 25) and patients with chronic anemia (i.e. mainly with sickle cell anemia; n = 32), at rest. While doppler echocardiography was able to detect difference in SVI between the two populations, the Physioflow® failed to detect any difference. Bland & Altman analyses have demonstrated no interchangeability between the two methods to assess CI and SVI in anemic patients and healthy subjects. While doppler echocardiography displayed a good concordance for SVI results with those obtained in the literature for anemic patients, the Physioflow® did not. Finally, in contrast to doppler echocardiography: 1) the CI obtained with the Physioflow® was not correlated with the hemoglobin level and 2) the stroke volume determined by the Physioflow® was highly influenced by body surface area. In conclusion, our findings indicate that the Physioflow® device is inaccurate for the measurement of SVI and CI in patients with chronic anemia and has a poor accuracy for the measurement of these parameters in African healthy subjects.

The pediatric hydroxyurea phase III clinical trial (BABY HUG): challenges of study design

Evidence of the laboratory benefits of hydroxyurea and its clinical efficacy in reducing acute vaso-occlusive events in adults and children with sickle cell anemia has accumulated for more than 15 years. A definitive clinical trial showing that hydroxyurea can also prevent organ damage might support widespread use of the drug at an early age. BABY HUG is a randomized, double-blind placebo-controlled trial to test whether treating young children ages 9-17 months at entry with a liquid preparation of hydroxyurea (20 mg/kg/day for 2 years) can decrease organ damage in the kidneys and spleen by at least 50%. Creation of BABY HUG entailed unique challenges and opportunities. Although protection of brain function might be considered a more compelling endpoint, preservation of spleen and renal function has clinical relevance, and significant treatment effects might be discernable within the mandated sample size of 200. Concerns about unanticipated severe toxicity and burdensome testing and monitoring requirements were addressed in part by an internal Feasibility and Safety Pilot Study, the successful completion of which was required prior to enrolling a larger number of children on the protocol. Concerns over recruitment of potentially vulnerable subjects were allayed by inclusion of a research subject advocate, or ombudsman. Finally, maintenance of blinding of research personnel was aided by inclusion of an unblinded primary endpoint person, charged with transmitting endpoint data and monitoring blood work locally for toxicity (ClinicalTrials.gov number, NCT00006400).

Non-congenital heart disease associated pediatric pulmonary arterial hypertension

Recognition of causes of pulmonary hypertension other than congenital heart disease is increasing in children. Diagnosis and treatment of any underlying cause of pulmonary hypertension is crucial for optimal management of pulmonary hypertension. This article discusses the available knowledge regarding several disorders associated with pulmonary hypertension in children: idiopathic pulmonary arterial hypertension (IPAH), pulmonary capillary hemangiomatosis, pulmonary veno-occlusive disease, hemoglobinopathies, hepatopulmonary syndrome, portopulmonary hypertension and HIV. Three classes of drugs have been extensively studied for the treatment of IPAH in adults: prostanoids (epoprostenol, treprostinil, iloprost, beraprost), endothelin receptor antagonists (bosentan, sitaxsentan, ambrisentan), and phosphodiesterase inhibitors (Sildenafil, tadalafil). These medications have been used in treatment of children with pulmonary arterial hypertension, although randomized clinical trial data is lacking. As pulmonary vasodilator therapy in certain diseases may be associated with adverse outcomes, further study of these medications is needed before widespread use is encouraged.

Evaluation of left ventricular diastolic function in pediatric sickle cell disease patients

Although cardiac involvement is common in adult sickle cell disease (SCD) patients, it is unknown when cardiac dysfunction appears in the course of SCD. Diastolic function has not been comprehensively analyzed in children with SCD. Thus, our aim was to evaluate diastolic function in pediatric SCD patients. Echocardiograms were performed in 156 (73 SC and 81 control) patients. Left ventricular and left atrial volumes, left ventricular mass, mitral inflow, and tissue Doppler indices (TDI) were obtained. The right ventricular pressures (RVP) were calculated. For each SCD patient, mean hemoglobin (Hb), fetal hemoglobin (HbF) levels, and blood transfusion encounters were recorded. Data were analyzed using t-test, univariate and multivariate regression, and Spearman correlation analyses. SCD patients had significantly larger left ventricular and atrial volumes than controls. Mitral inflow velocities were significantly higher in the SCD group. Of 73 SCD subjects, 32 had left ventricular dilatation, 11 had hypertrophy, and 25 had elevated RVP. Left ventricular size was inversely related to Hb, but unrelated to HbF or age. The early mitral inflow velocity was correlated negatively with Hb and positively with left ventricular sizes. TDI indices did not differ between the SCD and control groups. They were unrelated to Hg, HgF, transfusion history, or ventricular size; however, Doppler indices of left ventricular stiffness were increased in SCD patients. Pediatric SCD patients demonstrate increased left ventricular stiffness, and a significant percentage of them have left ventricular hypertrophy. There are strong positive relations between left ventricular hypertrophy and right ventricular pressure in these patients. TDI should be employed in the evaluation of SCD patients.

Right ventricular abnormalities in sickle cell anemia: evidence of a progressive increase in pulmonary vascular resistance

OBJECTIVE

To assess the effects of sickle cell anemia (SCA) on the right ventricle (RV).

STUDY DESIGN

Echocardiograms of 32 children with SCA were compared with age-matched healthy controls. RV measurements included diastolic area index, fractional area change, free-wall mass index, ejection time corrected for heart rate (ET(c)), and tricuspid regurgitation (TR) gradient.

RESULTS

SCA subjects had elevated RV ETc (mean +/- standard deviation, 0.369 +/- 0.030 sec vs 0.351 +/- 0.022 sec; P < .01), diastolic area index (19.9 +/- 2.4 cm(2)/m(2) vs 13.2 +/- 2.1 cm(2)/m(2); P < .01) and free-wall mass index (33.2 +/- 4.4 g/m(2) vs 23.9 +/- 4.3 g/m(2); P < .01), whereas RV fractional area change (37 +/- 8% vs 36 +/- 4%) was not different from controls. Although RV diastolic area index in SCA paralleled the normal range over time, RV free-wall mass index continued to gradually rise throughout childhood (r = .42; P < .05). TR gradients > 2.5 m/sec, consistent with pulmonary hypertension, were found in 5 (16%) of SCA subjects, all older than 9 years.

CONCLUSIONS

RV preload and systolic function do not worsen during childhood in SCA; however, RV mass index and the prevalence of pulmonary hypertension increase consistent with rising pulmonary vascular resistance.

Left ventricular diastolic filling abnormalities identified by Doppler echocardiography in asymptomatic patients with sickle cell anemia

To determine whether left ventricular diastolic abnormalities are an early feature of sickle cell anemia, indexes of diastolic filling were obtained with pulsed Doppler echocardiography in 30 consecutive patients with this disease (mean age 29 years; range 19 to 39) who had not experienced symptoms of heart failure and had normal left ventricular systolic function. Data were compared with those in 30 normal control subjects of similar ages. Seventeen (57%) of the 30 patients with sickle cell anemia had evidence of abnormal left ventricular diastolic filling. Six of these 17 patients had a Doppler pattern consistent with "restrictive" filling, characterized by reduced early diastolic deceleration time (less than 110 ms) or an increased rate of decline of early flow velocity (EF slope greater than 7.4 m/s2), or both, as well as decreased late diastolic velocity-time integral (2.6 +/- 0.7 vs. 3.4 +/- 0.8 cm in normal subjects; p less than 0.05). Another 11 patients showed a Doppler waveform consistent with impaired relaxation, characterized by prolonged deceleration time (greater than 166 ms) or reduced EF slope (less than 3.8 m/s2), as well as increased late diastolic velocity-time integral (4.0 +/- 0.5 vs. 3.4 +/- 0.8 cm in normal subjects; p = 0.03). This Doppler echocardiographic analysis demonstrates that left ventricular diastolic filling patterns are altered in patients with sickle cell anemia and that these diastolic abnormalities may be present in the absence of symptoms of heart failure. These abnormal patterns suggest an intrinsic myocardial abnormality in patients with sickle anemia and may prove to be early markers of cardiac disease.

Left ventricular function in mild hypertension after adrenergic blockade

We previously used the Doppler transmitral flow velocity ratio A/E (A = late ventricular filling peak velocity; E = early ventricular filling peak velocity) and the age-adjusted ratio A/E/Age to detect left ventricular filling abnormalities in untreated mild hypertension. This study is a double-blind assessment of the effect of combined alpha- and beta-blockade (labetalol) and beta-blockade alone (atenolol) on left ventricular filling in mild hypertension. Twenty-seven patients blindly randomized to labetalol (12 patients) and atenolol (15 patients) treatment completed the echocardiographic and Doppler studies. Clinical and echo-Doppler data obtained at baseline and 6 weeks after initiation of therapy showed no difference between the two groups for age (49 +/- 10 vs 46 +/- 10 years), mean blood pressure (before therapy, 118 +/- 9 vs 117 +/- 8 mm Hg; after therapy, 108 +/- 12 mm Hg), left ventricular dimensions, wall thickness, systolic function, and mean late filling velocity A. There was no significant change in left ventricular mass and mass index with labetalol (left ventricular mass, 211 +/- 36 vs 216 +/- 38; mass index, 110 +/- 17 vs 112 +/- 16) or atenolol (245 +/- 41 vs 271 +/- 65; 120 +/- 18 vs 130 +/- 35). The mean velocity E, A/E, and A/E/Age ratios significantly improved with labetalol (p less than 0.05) but did not change significantly with atenolol. The improvement in A/E and A/E/Age ratios was primarily due to an increase in early filling velocity E.(ABSTRACT TRUNCATED AT 250 WORDS)