Noninvasive assessment of elevated pulmonary vascular resistance in children with pulmonary hypertension secondary to congenital heart disease: A comparative study between five different Doppler indices

Background

Pulmonary vascular resistance (PVR) is an important hemodynamic parameter in patients with congenital heart disease (CHD). Noninvasive estimation of PVR represents an attractive alternative to invasive measurements.

Methods

The study included 175 patients with pulmonary hypertension (PH) secondary to CHD. All patients underwent full echocardiographic study and invasive hemodynamic measurements. The study population was then subdivided into four subgroups. Each of the following Doppler indices was measured in one of these four subgroups: peak tricuspid regurgitant velocity (TRV), the ratio of the TRV to the velocity time integral of the right ventricular outflow tract (TRV/TVI_RVOT), peak velocity of tricuspid annular systolic motion (TSm), heart rate corrected acceleration time and infliction time of the proximal left pulmonary artery (ATc, InTc). The data obtained was correlated with invasive PVR measurement. An ROC curve analysis was done to generate cutoff points with the highest balanced sensitivity and specificity to predict PVR > 6WU/m². The receiver operating characteristics (ROC) curves were compared with each other to determine the most reliable cutoff point in predicting elevated PVR > 6WU/m².

Results

There was a significant correlation between both the TRV and TSm and invasive measurement of PVR (r = −0.511, 0.387 and P value = 0.0002, 0.006 respectively). The TSm and TRV cutoff values were the most reliable to predict elevated PVR > 6 WU/m². A TSm cutoff value of ⩽16.16 cm/s provided the best balanced sensitivity (85.7%) and specificity (66.7%) to determine PVR_CATH > 6 WU/m². A cutoff value less than 7.62 cm/s had 100% specificity to predict PVR_CATH > 6 WU/m². A TRV cutoff value of >3.96 m/s provided the best balanced sensitivity (66.7%) and specificity (100%) to determine PVR_CATH > 6 WU/m². Both TRV and TSm had the highest area under the ROC curve among the 5 DOPPLER indices studied.

Conclusion

Prediction of elevated PVR in children with PH secondary to CHD could be achieved noninvasively using a number of Doppler indices. Among the five Doppler indices examined in the current study, the peak TRV and the TSm of the lateral tricuspid annulus had the highest balanced sensitivity and specificity to predict PVRI > 6 WU/m².Abbreviations: AcT, acceleration time; AcTc, acceleration time corrected to heart rate; BSA, body surface area; CHD, congenital heart disease; DTI, Doppler tissue imaging; InT, inflection time; InTc, inflection time corrected to heart rate; MPAP, mean pulmonary artery pressure; PA, pulmonary artery; PCWP, pulmonary capillary wedge pressure; PH, pulmonary hypertension; PVR, pulmonary vascular resistance; Qp, pulmonary blood flow; ROC, receiver operating characteristics curves; RVSP, right ventricular systolic pressure; TRV, peak tricuspid regurgitant velocity; TSm, peak velocity of tricuspid annular systolic motion; TVI_RVOT, right ventricular outflow tract time–velocity integral