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branches are being assessed, especially in relation to surrounding structures, they are less helpful in assessment of the pulmonary valve However, future technologic advances in the speed of acquisition of images, ECG gating, and postprocessing may enhance the utility of MRI in the evaluation of isolated pulmonary valve stenosis At present, however, it is likely that more information about the morphology of the pulmonary valve will be available with echocardiography (including three-dimensional echo) FIG 42.23 Three-dimensional volume-rendered reconstruction of the right ventricular outflow tract (images acquired with contrast-enhanced magnetic resonance angiography) Note the narrowing of the pulmonary trunk and gross dilation of the left pulmonary artery (Courtesy Andrew Taylor, Consultant Cardiac Radiologist, Great Ormond Street Hospital for Children, London.) Cardiac Catheterization and Angiography Diagnostic cardiac catheterization has been almost completely superseded by less invasive techniques, such as echocardiography, for the assessment of pulmonary valve stenosis, and is now undertaken only to perform catheter interventions or if additional associated anomalies (such as branch pulmonary artery stenosis) warrant cardiac catheterization The one advantage of cardiac catheterization over other imaging techniques is the accurate measurement of ventricular and pulmonary arterial pressures It is important to remember that in contrast to Doppler echocardiography, which estimates peak instantaneous differences in pressure across the stenosis (see Fig 42.19), gradients obtained in the catheterization laboratory through a pullback technique show a peak-to-peak difference in pressure between the sites of measurement, which is usually up to 25% to 40% lower than the peak instantaneous Doppler gradient (Fig 42.24) Importantly though, hemodynamic evaluation alone does not justify a diagnostic cardiac catheterization unless the patient is considered for possible balloon pulmonary valvuloplasty FIG 42.24 Peak-to-peak pullback gradient measured at cardiac catheterization Key Diagnostic Features The key features are summarized in Box 42.1 Box 42.1 Key Diagnostic Features of Pulmonary Valvar Stenosis Physical Examination ▪ Physical signs of right ventricular hypertrophy ▪ Systolic ejection click (unless severe) ▪ Ejection systolic murmur, second left intercostal space and back ▪ Wide splitting of the second heart sound (depending on severity) ▪ Reduced intensity of P2 (depending on severity) ▪ Associated thrill (depending on severity) Investigations ▪ Right ventricular hypertrophy on electrocardiogram ▪ Echocardiography ▪ Thickened and doming valve ▪ Evidence of turbulence and flow acceleration at pulmonary valve
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