Doppler of pulmonary stenosis before and after balloon valvuloplasty

The Doppler signal is directed through the suprasternal notch. Prior to valvuloplasty (panel 1) the estimated peak systolic gradient is 35 to 40 mmHg; however, the Doppler underestimates the peak gradient because sampling of flow may not be axial. After valvuloplasty (panel 2), there is a decrease in peak velocity to 2 m/sec, and the estimated gradient is 16 mmHg.