Andersons pediatric cardiology 1117

FIG 42.21 Color-comparison image in the sagittal plane of a fetus with pulmonary stenosis The two-dimensional image on the left shows the location of the pulmonary valve The color-flow Doppler image on the right demonstrates corresponding flow turbulence originating at that point Fetal echocardiography is indicated when congenital heart disease is suspected, which, in the absence of other indications, is often following routine obstetric ultrasound assessment Fetal echocardiography is frequently performed between 18 and 22 weeks of gestation, but examinations are sometimes performed earlier in selected high-risk cases Given that image resolution may preclude diagnosis or that certain lesions (such as pulmonary stenosis) can be subtle and/or progress, current recommendations are to repeat the assessment for those undergoing fetal echocardiography in early gestation.35 Fetal echocardiography is limited in predicting postnatal disease due in part to both postnatal physiologic changes and progression of disease Therefore a normal fetal echocardiogram should not preclude postnatal assessment when there is clinical suspicion of congenital heart disease At present prenatal diagnosis of pulmonary stenosis by fetal echocardiography is limited to parental counseling and monitoring for the progression of disease with serial examinations In cases where moderate or severe stenosis is suspected, admission to a neonatal intensive care unit for monitoring and prompt cardiology assessment should be considered Fetal cardiac intervention in pulmonary stenosis is not currently routinely used and is limited to cases of pulmonary atresia/intact ventricular septum with evolving right ventricular hypoplasia.36 Magnetic Resonance Imaging and Computed Tomography For most patients with isolated pulmonary valve stenosis, echocardiography is the main imaging tool to estimate the valvar gradient, and indication for transcatheter therapy is usually based on a combination of echocardiographic and clinical data Although cross-sectional techniques, such as magnetic resonance angiography (Fig 42.22) or computed multislice spiral tomography, are considered to be less invasive than cardiac catheterization, these imaging modalities are rarely needed in the evaluation of simple pulmonary valve stenosis If the baseline gradient by echocardiography suggests the need for (transcatheter) intervention, then adding computed multislice spiral tomography prior to cardiac catheterization would expose the patient to additional radiation without necessarily adding to the medical decision making at the time of cardiac catheterization Conversely, in a patient who does not meet any indication for valvar intervention based on echocardiographic data, adding computed tomography evaluation is unlikely to change management FIG 42.22 Oblique sagittal balanced steady-state free precession magnetic resonance images of the right ventricular outflow tract showing stenosis of the pulmonary trunk (Courtesy Andrew Taylor, Consultant Cardiac Radiologist, Great Ormond Street Hospital for Children, London.) Cardiac magnetic resonance imaging (MRI) and angiography may have a role in selected patients and has an advantage over computed tomography evaluation due to the lack of radiation exposure These imaging modalities may complement (not supplement) standard imaging in selected patients, such as those with supravalvar pulmonary stenosis Furthermore, they offer the ability to not only obtain anatomic dimensions but also physiologic data such as right ventricular function and volumes, estimated gradients, and pulmonary regurgitant fraction.37,38 However, advantages in small children may still be offset by the need for general anesthesia in some patients, even though advances have allowed the technique to expand to smaller children without general anaesthesia.39 Whereas cross-sectional techniques, particularly three-dimensional reconstructions (Fig 42.23), are helpful when the pulmonary trunk and its .. .cardiology assessment should be considered Fetal cardiac intervention in pulmonary stenosis is not currently routinely used and is limited to cases of