Elevated Tricuspid Regurgitant Jet Velocity in Children and Adolescents with Sickle Cell Disease: Association with Hemolysis and Hemoglobin Oxygen Desaturation

Background. Echocardiography-determined tricuspid regurgitant jet velocity >2.5 m/sec predicts elevated systolic pulmonary artery pressure and early mortality in adults with sickle cell disease (SCD). The definition, prevalence and clinical correlates of elevated jet velocity have not been established in pediatric patients. Methods. A prospective, case controlled, multi-center study of 310 children and adolescents with SCD under basal conditions was conducted to test the hypotheses that elevated jet velocity affects 10–20% of pediatric patients, is associated with both hemolysis and hypoxia, and has clinical correlates of acute chest syndrome, stroke, high transfusion requirement and abnormal six-minute-walk test. Results. Elevated jet velocity (defined as ≥2.60 m/sec based on the mean ±2 SD in 54 controls) occurred in 32 patients (11%; 95% confidence interval 8–15%). A hemolytic index (generated by principal component analysis of lactate-dehydrogenase, aspartate-aminotransferase, bilirubin and reticulocytes), and oxygen saturation ≤98% had independent associations with elevated jet velocity (P=0.009 and P=0.028, respectively) that persisted after adjustment for hemoglobin, systolic blood pressure and left ventricular diastolic function. Significant clinical correlates of elevated jet velocity included histories of acute chest syndrome and multiple blood transfusions and degree of oxygen desaturation during the six-minute-walk, but not history of stroke or six-minute-walk distance. Conclusion. This prospective study indicates an 11% prevalence of elevated jet velocity according to a pediatric-specific definition and provides evidence for independent associations with hemolysis and oxygen desaturation. Given these associations and the correlation with acute chest syndrome, elevated jet velocity may predict severe SCD complications, and future investigations should address whether early intervention is beneficial. | | N | Tricuspid regurgitant jet velocity<2.6 m/sec | N | Tricuspid regurgitant jet velocity≥2.6 m/sec | P value | |:-----------------------------------------------------------------------------------------------------:| --- | -------------------------------------------- | -- | -------------------------------------------- | ------- | | *number (%) | | ** Derived from reticulocyte count, lactate dehydrogenase, total bilirubin, asparate aminotransferase | | 1Adjusted for age and study site | | Marker of systemic blood pressure | | | | | | | Systolic blood pressure (mmHg) | 258 | 112 (103–120) | 32 | 118 (109–128) | 0.0301 | | Marker of anemia | | | | | | | Hemoglobin (g/dL) | 251 | 9.3 (8.2–10.6) | 30 | 9.1 (7.6–10.0) | 0.0411 | | Markers of hemolysis | | | | | | | Reticulocytes (%) | 244 | 6.8 (3.9–11.5) | 30 | 9.6 (4.4–14.60 | 0.0061 | | Reticulocyte count (K/uL) | 245 | 210 (148–309) | 30 | 248 (120–352) | 0.0501 | | Lactate dehydrogenase(U/L) | 247 | 356 (270–496) | 29 | 457 (342–570) | 0.0091 | | Total bilirubin (mg/dL) | 253 | 2.1 (1.3–3.3) | 30 | 2.8 (2.3–5.3) | 0.0051 | | Asparate aminotransferase (U/L) | 253 | 38 (29–52) | 30 | 47 (35–64) | 0.0011 | | Hemolytic index (relative unit)** | 237 | −0.08 (−1.22–0.91) | 28 | 0.91 (−0.10–2.50) | 0.00021 | | Marker of hypoxia | | | | | | | Oxygen saturation (%) | 250 | 99 (97–99) | 30 | 97 (96–98) | 0.0051 | Distribution of markers prospectively hypothesized to be associated with pulmonary hypertension according to tricuspid regurgitant jet velocity categories. Results are in median and interquartile range unless otherwise indicated.