Doppler evaluation of physiologic peripheral pulmonic stenosis in newborns

A common systolic ejection murmur of the neonate has been attributed to physiologic peripheral pulmonic stenosis. We investigated this auscultatory finding using duplex pulsed Doppler. Three groups of normal fuliterm neonates less than one week old were studied—10 without murmurs, 10 with grade 1/6 murmurs and nine with at least grade 2/6 murmurs. We measured the anatomical size and peak flow velocities in the main pulmonary artery and left and right branches, the peak velocity in the right ventricular outflow tract, and the bifurcation angle. Flow gradients were calculated as 4 (Vmax)2 Groups were compared by t-tests. A loud peripheral pulmonic stenosis murmur was associated with increased pulmonary artery velocities, with left pulmonary artery velocity the most discriminating variable (1.3 ± 0.29 vs 0.94 ± 0.19 m/s; p ≤ 0.05). Although the peak gradient never exceeded 12 mmHg, there was an increased gradient in the loud murmur group (8.7 ± 2.6 vs 5.7 ± 2.2 mmHg; p ≤ 0.05) which may even be underestimated by the lack of angle correction. The left pulmonary artery diameter was also larger in the loud murmur group, but there were no other anatomic or volumetric flow differences between groups. The soft murmur group could not be separated from normals. We conclude that Doppler techniques can confirm the physiologic basis of peripheral pulmonic stenosis murmurs.