FIG 42.14 Two-dimensional image in the parasternal short-axis view shows discrete stenosis in the subvalvar region of the pulmonic valve FIG 42.15 Color-comparison images in the parasternal short-axis view obtained from a patient with supravalvar pulmonic stenosis (A) Twodimensional image demonstrating discrete narrowing of the main pulmonary artery in the supravalvar region of the pulmonic valve (B) Colorflow Doppler image demonstrating flow turbulence originating in the supravalvar region and corresponding with the site of stenosis seen on the left-sided two-dimensional image FIG 42.16 Parasternal short-axis view demonstrating poststenotic dilation of the pulmonary trunk FIG 42.17 The diameter of the pulmonary valve at the hemodynamic ventriculoarterial junction can be measured accurately with echocardiography to aid in intervention planning Distal to the valve, it is possible to identify stenosis within the proximal pulmonary arterial tree, although other forms of imaging are necessary to assess pulmonary arterial pathology distal to the bifurcation The presence of additional abnormalities, such as atrial septal defects, can be recorded Three-dimensional echocardiography is being used more frequently in the imaging of congenital heart defects due to its ability to provide more detailed noninvasive imaging of these anomalies Specifically, with regard to pulmonic valve stenosis, three-dimensional echocardiography may provide better visualization of the morphology and function of the pulmonic valve.30 Although it enhances visualization of the morphologic features of the pulmonic valve, it is uncommon that three-dimensional echocardiography yields additional information affecting clinical management in pulmonary valve stenosis over traditional methods, such as color-flow and Doppler gradient assessment Previously, ECG was the mainstay of noninvasive assessment of the severity of pulmonary valve stenosis despite ECG correlates of right ventricular hypertrophy being relatively weak Since the advent of Doppler echocardiography, assessment is greatly simplified Color-flow Doppler shows turbulent blood originating at the point of stenosis (Fig 42.18; Videos 42.2 and 42.3) Both pulsed and continuous-wave interrogations permit measurement of the maximal velocity of the flow across the stenosis (Fig 42.19) The pressure gradient can be estimated more accurately using the modified and simplified Bernoulli equation, where the valvar pressure gradient, expressed in millimeters of mercury or ΔP, is calculated from the maximal Doppler velocity at meters per second, or V, across the pulmonary valve: