Description

The PDA can be visualized from the high left parasternal ‘ductal’ view. Using a combination of colour and either pulse or continuous wave Doppler the direction and peak velocity of flow can be measured. PASP can be calculated if systemic systolic blood pressure (SSBP) is known by one of the following two equations: PASP = SSBP + (4 x V2max) if right to left shunt is > 30% of cardiac cycle where Vmax is the peak velocity of right to left flow across the PDA. PASP = SSBP - (4 x V2 max) if right to left shunt is < 30% of cardiac cycle where Vmax is the peak velocity of left to right flow across the PDA. Although TR jet or PDA can be individually absent in 15-30% of babies with PPHN, it is usually possible to measure PASP in most babies at the time of presentation by using one of the two methods. These methods might not remain as useful for subsequent monitoring as with time the PDA can close or become restrictive and the TR jet can become undetectable especially in the presence of right ventricle dysfunction.

This loop demonstrates bidirectional shunting across the PDA. The PVR is estimated to be similar to the SVR in this case.