Accuracy of Echocardiographic Measures for Diagnosing Pulmonary Hypertension in Children with Sickle Cell Anaemia

Background: Echocardiography has evolved to be a non-invasive tool in the assessment of cardiac haemodynamic including pulmonary artery pressures, especially among people at risk of developing pulmonary hypertension. However, concerns were raised over time regarding the contrasting figures of the prevalence of pulmonary hypertension using the conventional peak tricuspid regurgitation jet velocity alone when compared with echo-derived mean pulmonary artery pressure. This analytical cross-sectional study aimed to compare the use of the two measurements in the echocardiographic evaluation of pulmonary artery pressures in children with sickle cell anaemia (SCA). Three hundred children aged 6 months to 15 years with confirmed diagnosis of SCA in steady state, and age and gender- matched controls were studied. Pulmonary pressure was assessed using Doppler echocardiography from apical 4 chamber RV focused view and parasternal short axis view through Doppler interrogation of the tricuspid regurgitation jet (TRJ). Normal pulmonary artery pressure was defined as tricuspid regurgitation jet velocity (TRV) of less than 2.5 m/s, elevated pulmonary artery pressure (PAP) when the TRV is greater than or equals to 2.5 m/s, and pulmonary hypertension (PH) was defined as a mean pulmonary artery pressure (MPAP) >20 mmHg estimated from mean gradient (MG) derived from the area under the curve of the interrogated TRJ, plus estimated right atrial pressure. Sixty-four participants with SCA (21.3%) were found to have elevated PAP as against 19 (6.3%) controls. While none of the controls had PH, 17 (5.7%) participants with SCA had MPAP > 20 mmHg diagnostic of pulmonary hypertension. Although there was strong positive correlation between measured peak TRV and MG (R 2 = 0.801, p < 0.001), quite a number of subjects with elevated PAP were found not to have high MPAP enough to be diagnostic of PH. Although high peak TRV is a surrogate marker of elevated PAP in children with SCA, it’s not diagnostic of PH when compared with estimated MPAP using the mean gradient and estimated RA pressure.