Children aged below 12 years undergoing elective cardiac surgery for congenital heart disease with left to right shunt with prior evidence of pulmonary arterial hypertension on preoperative echocardiography

After induction of anaesthesia and stabilization of hemodynamics, transthoracic echocardiography will be done on a GE Vivid e9 workstation (GE Vingmed, Horton, Norway) with MS5 transthoracic probe with synchronized ECG.

From TTE the following views and measurements will be acquired :

• Apical four chamber (A4C) view
• Apical two chamber view (A2C) view
• Right ventricle (RV) focused A4C view
• Right ventricular systolic pressure (RVSP)
• Pulmonary arterial acceleration time (PAAT),
• Tricuspid annular plane systolic excursion (TAPSE),
• Tricuspid annular plane systolic velocity (s'),
• Right ventricular fractional area change (RV FAC)
• RV free wall strain,
• RV myocardial performance index (MPI),
• RV isovolumic relaxation time (IVRT),
• RV isovolumic acceleration time (IVA)

Invasive PA pressure measurement will be done after surgical exposure with a fine needle and a zeroed transducer by the Surgeon.

RA strain estimation will be done from the TTE images in RV focused A4C view, tracing the endocardial border from tricuspid annulus to tricuspid annulus along RA lateral wall to roof to septal wall.

After optimizing the region of interest and automated speckle tracking for longitudinal strain and the following parameters will be measured :

• RA reservoir strain : difference of the strain value at tricuspid valve opening minus ventricular end-diastole (positive value).
• RA conduit strain : difference of the strain value at the onset of atrial contraction minus tricuspid valve opening (negative value).
• RA contractile strain : difference of the strain value at ventricular end- diastole minus onset of atrial contraction (negative value).

From TTE the following views and measurements will be acquired :

Apical four chamber (A4C) view Apical two chamber view (A2C) view Right ventricle (RV) focused A4C view Right ventricular systolic pressure (RVSP) Pulmonary arterial acceleration time (PAAT), Tricuspid annular plane systolic excursion (TAPSE), Tricuspid annular plane systolic velocity (s'), Right ventricular fractional area change (RV FAC) RV free wall strain, RV myocardial performance index (MPI), RV isovolumic relaxation time (IVRT), RV isovolumic acceleration time (IVA)