Patent Ductus Arteriosus (PDA) on Echocardiogram Another great teaching clip, this time a patent ductus arteriosus (PDA). Continuous Ao-to-PA flow. CW Doppler showing continuous but fluctuating flow. Vivek Kulkarni MD @VivekKulkarniMD #Patent #Ductus #Arteriosus #PDA #Echocardiogram #cardiology #pocus #clinical