Estimation of pulmonary artery pressure using continuous wave Doppler echocardiogram interrogation in a patient with a patent ductus arteriosus

Doppler echocardiogram interrogation is directed into the jet of continuous left-to-right flow in the short axis view of a patient with a patent ductus arteriosus (PDA). The maximum velocity (V) of 2.8 m/sec through the ductus arteriosus is noted by continuous wave Doppler. The peak gradient between the aorta and pulmonary artery is 4 x V² or 32 mmHg. The estimated pulmonary artery pressure of 36 mmHg is the difference between the measured systolic blood pressure of 68 mmHg and the peak gradient of 32 mmHg between the aorta and pulmonary artery.