arrangements Analysis of the Ventriculoarterial Junctions When assessing the junctions between the ventricles and the arterial trunks, it is necessary first to identify ventricular morphology, using the methods already described, and then to establish the arrangement of the arterial trunks In infants and small children, the latter information is usually derived from subcostal longaxis and short-axis sweeps This is generally supplemented by other echocardiographic sections, like the high parasternal short- and long-axis views The aorta is characterized by identifying the origin of the brachiocephalic arteries from the arch The pulmonary trunk is recognized on the basis of its bifurcation into right and left branches A common arterial trunk is a solitary arterial trunk giving rise in its ascending part to the coronary and pulmonary arteries and the ascending aorta Having established the connections across the ventriculoarterial junctions, it is also important separately to determine the arrangement of the arterial valves, the relationship between the arterial trunks, and the infundibular morphology These features are all independent of one another and independent of the ventriculoarterial connections Establishing each feature separately, and describing them all, removes the potential for ambiguity (see Chapter 1) Pediatric Transesophageal Echocardiography Transesophageal echocardiography is complementary to transthoracic echocardiography in the diagnosis and monitoring of infants and children with congenitally malformed hearts.7 Miniaturization of the transesophageal probes has allowed this technique to be applied to children weighing from approximately 3 to 3.5 kg The technique has an important role in documenting the adequacy of surgical repair immediately after the discontinuation of cardiopulmonary bypass and in the early postoperative period in the intensive care unit where transthoracic windows can be limited In most centers, perioperative transesophageal imaging is performed during nearly every surgical intervention and has been shown to have an important impact on the surgical results and need for reinterventions Transesophageal imaging is also indicated for monitoring various procedures used during interventional catheterization It can also be indicated for patients with inadequate transthoracic windows, although alternative imaging techniques like cardiac magnetic imaging are usually preferred in children Transesophageal examinations should be performed using systems offering cross-sectional imaging, color Doppler, continuous wave, and pulsed wave Doppler, as well as tissue Doppler Multiplane pediatric transesophageal probes are currently available for use in children weighing from 3 to 20 kg Epicardial imaging might still be a good alternative for smaller infants in case of difficult probe insertion or airways issues caused by probe compression The adult multiplanar probes designed for use in adults can be used in patients weighing more than 20 kg Recently, an adult-sized three-dimensional transesophageal probe, which is approximately 2 mm thicker compared with the adult multiplanar probe, has become available, allowing real-time three-dimensional transesophageal imaging This probe can be used only in children greater than 20 kg, but it is expected to be miniaturized for future use in children The probes should always pass easily without significant resistance Complications are rare but include esophageal perforation, along with compression of vessels and airways Nonetheless, because of these rare complications, continuous monitoring of the hemodynamic and respiratory state is always required Transesophageal echocardiography therefore requires at least two attending physicians, one to manage the airway and monitor the patient and the other to perform the examination For most infants and children, the studies are performed under general anesthesia, using tracheal intubation under the supervision of an anesthesiologist For examination of intubated patients in the intensive care unit, and for study of adolescents, sedation is usually sufficient Deep sedation may be adequate in an outpatient setting in adolescents and adults The absolute contraindications to a transesophageal examination are the presence of any pharyngeal or esophageal lesion predisposing to laceration or perforation during manipulation of the probe In addition, some patients with tracheomalacia may manifest a fall in systemic arterial saturation when the probe is manipulated because of tracheal compression Although bacteremia has been reported, the need for prophylaxis against bacterial endocarditis remains controversial In the most recent published guidelines, the risk for bacterial endocarditis due to patients undergoing a gastrointestinal procedure was judged to be exceedingly small, not justifying the prophylactic use of antibiotics.8 Technique of Examination After induction of general anesthesia and endotracheal intubation, or following appropriate sedation, the head of the patient is positioned in the midline, or slightly to the left, the mouth opened with the jaw thrust forward, and the neck slightly extended The unlocked tip of the probe is lubricated with a watersoluble gel, gently introduced into the hypopharynx, and advanced until an image of the heart is displayed on the screen If there is resistance to passage of the transducer, a laryngoscope can be used to permit introduction under direct vision Once the transducer is appropriately positioned, the head of the patient can be maintained in the midline or placed to face the echocardiographer The probe is then manipulated to obtain a range of transesophageal planes A series of transgastric sections can be obtained by manipulating the tip of the probe when it has been advanced into the stomach In contrast to transthoracic echocardiography, there is less flexibility in the imaging planes Multiplanar imaging allows rotation of the imaging plane between 0 and 180 degrees Zero corresponds to a transverse view, whereas 90 degrees corresponds to a more longitudinal view Use of specific angles to obtain certain images is not very useful because the morphology might differ between individuals The American Society of Echocardiography has issued guidelines for orientation of images, which can be used as a reference For those with complexly malformed hearts, unusual imaging planes might be required Some of the standard images are further discussed Transesophageal Views Midesophageal Four-Chamber View In a transverse plane, at around zero, it is possible to produce a four-chamber view, imaging the atrioventricular valves, the ventricles, and the atrial and ventricular septums (Fig 19.30) The images produced are shown with the apex down, and with the left ventricle to the right of the screen When slightly moving the probe upwards, the atrial septum can be seen Slight rotation to the left at atrial level allows visualization of the left pulmonary veins, and slight rightward rotation reveals the right pulmonary veins Adding color Doppler with a low Nyquist limit might help to identify the pulmonary veins from this view By very slight upward and downward motion, it is possible to distinguish the upper and lower left and right pulmonary veins The apical four-chamber view is well suited to the assessment of atrioventricular valvar function Using color Doppler ... cross-sectional imaging, color Doppler, continuous wave, and pulsed wave Doppler, as well as tissue Doppler Multiplane pediatric transesophageal probes are currently available for use in children weighing from 3 to 20 kg