Measurement of PAS
First, in the parasternal short axis window, we obtained the pulmonary
artery. Thereafter, the pulmonary blood flow Doppler recordings were
measured under the semilunar pulmonic valve. The MFS (maximum frequency
shift) of the pulmonary flow was recorded for at least 5 succeeding
beats. The PfAT, which is described as the distance between the starting
of systolic pulmonary artery flow and peak flow rate, was measured for
at least 5 succeeding beats. The PAS value was then obtained by dividing
average MFS by average PfAT (Fig. 1 ). Intra- and inter-observer
agreements were 0.97 and 0.93 for PAS measurements, respectively
(p < 0.001).