A guide to echocardiographic assessment in children and adolescents with pulmonary hypertension

Abstract

While the current definition of pulmonary hypertension (PH) is still based on haemodynamic variables, transthoracic echocardiography is the most important diagnostic clinical tool for the first assessment and evaluation of a patient, in whom PH is suspected. In addition, it is the most important clinical modality in long term follow-up and the utility of echocardiography has widely been demonstrated in patients with PH. Echocardiography not only reveals the underlying cardiac morphology and diagnosis of any associated cardiac defects. In most patients with PH right ventricular (RV) pressure estimation is feasible. In addition, ventricular systolic and diastolic function, as well as ventricular-ventricular interactions of both ventricles can be assessed by using echocardiography. Maximizing the use of echocardiography by reporting several measures to gain information and quantitatively describe the parameters, that are linked to prognosis, seem particularly appealing in these children, in whom other advanced imaging modalities requiring anaesthesia is associated with a considerable risk. Herein we provide a practical approach and a concise and clinically applicable echocardiographic guidance and present basic variables, which should be obtained at any assessment. Moreover, we present additional advanced echocardiographic measures, that can be applied in a research or clinical setting when progressive PH needs a deeper insight to assess heart function, estimation of pulmonary artery pressures among others, by echocardiography. Finally, clinically relevant studies in view of the prognostic properties with a focus on the most important echocardiographic variables in pediatric PH are summarized.

Keywords: Pulmonary hypertension; children; echocardiography.

Figure 1

CW-Doppler interrogation of the tricuspid regurgitation signal from an apical 4-chamber view. Measurement of maximal velocity to estimate systolic right ventricular/pulmonary artery pressures by using the modified Bernoulli-equation and addition of right atrial pressure (in the absence of any right ventricular outflow tract obstruction or pulmonary stenosis).

Figure 2

2D measurement of inferior caval vein (IVC) from a transabdominal view close to the IVC-right atrial insertion. Absolute dimension of IVC can be measured or reported as IVC collapsibility index = (maximal IVC diameter – minimal IVC diameter): max. IVC diameter × 100.

Figure 3

PW Doppler of antegrade flow into the pulmonary artery with measurement of the pulmonary acceleration time (PAAT). Interval from the onset of flow in the pulmonary artery to peak velocity of the flow signal (in ms).

Figure 4

TAPSE measurement from an apical 4-chamber view, by placing the M-mode over the anterior right ventricular free wall at the level of the tricuspid valve insertion.

Figure 5

Left ventricular eccentricity index (LVEI) is measured from a parasternal short axis view of the ventricles, expressed as ratio of the minor axis of the LV parallel to the interventricular septum divided by the minor axis perpendicular to the septum.

Figure 6

Right ventricular (RV) fractional area change (RV-FAC) is measured in an apical 4-chamber view by tracing the inner surface of the right ventricle in end-diastole and in systole. The FAC is reported as ratio of the (diastolic RV area − the systolic RV area)/diastolic RV area.

Figure 7

Systolic-diastolic duration ratio can be obtained from CW Doppler flow measurement of the tricuspid regurgitation (TR) signal of S and D from an apical 4-chamber view. The duration of the TR flow reflects S, while D is measured from the end of the TR flow signal to the new onset of TR in the next cardiac cycle.

Figure 8

RV base/apex ratio is measured is obtained at end-systole from an apical 4-chamber view. The RV internal diameter is measured at the base of the RV (RVES base), apical to the tricuspid valve anulus, whereas the apical internal diameter is taken at the level of the distal end of the moderator band (RVES apex).

Figure 9

Tissue Doppler Imaging from an apical 4-chamber view with PW—Doppler placed on the right ventricular anterior wall at tricuspid valvar ring level.