Transesophageal Echocardiography for Congenital Heart Disease by Pierre C. Wong & Wanda C. Miller-Hance

Author:Pierre C. Wong & Wanda C. Miller-Hance
Language: eng
Format: epub
Publisher: Springer London, London

Fig. 9.11Double chambered right ventricle (RV) as seen from the modified deep transgastric sagittal view (multiplane angle about 70°). (a) Shows the prominent mid-cavitary muscle bundles in the right ventricle. (b) Shows turbulent color flow Doppler across these muscle bundles. Note that this view provides an excellent angle for spectral Doppler evaluation of the RV outflow tract. LV left ventricle, PA pulmonary artery

It should be noted that deep transgastric views are not always available. For example, in some instances of dextrocardia where the stomach and the heart are not on the same side of the body, this view might be difficult or impossible to obtain.

When evaluating the ventricular septum by TEE, color flow Doppler is an essential component of the examination. With color Doppler, a small VSD not visible by 2D imaging becomes apparent. Also, the magnitude and direction of a shunt can be assessed. It is important to remember that, given the range of congenital heart lesions and physiology that can be encountered, a defect in the ventricular septum might not always shunt from left to right. If a patient has pulmonary hypertension and a defect is seen by 2D imaging, once color is added, the characteristic appearance of aliasing seen with high velocity flow might not be present. Instead there may only be a low velocity non-aliased left to right shunt or even a right to left shunt. Thus the direction of flow by color Doppler is important to facilitate the physiologic assessment. In addition to color flow Doppler, spectral Doppler can help assess the direction and gradient of the flow through a defect (although an optimal spectral Doppler angle might not be available).

It is also important to remember that in the presence of a large defect, there may be additional smaller muscular defects not readily seen since the ventricular pressures are similar and the majority of the blood flow is through the larger defect. To aid in the detection of these defects, the color flow Doppler Nyquist limit can be decreased to identify lower velocity shunts However in some cases the smaller defects might not be detected until the postoperative evaluation; after the larger defect is closed and there is now a larger pressure differential between the two chambers, the smaller defects become more readily apparent. Moreover in some instances an apparently large, single muscular VSD reveals upon closer inspection that it is actually comprised of two smaller defects separated by a muscle bridge or bundle. Identification of this type of defect has important surgical implications. The potential for multiple VSDs underscores the importance of performing a complete and thorough TEE evaluation of all portions of the ventricular septum, using both 2D imaging and color flow Doppler.

As a general rule, it is recommended that the echocar-diographer perform as much 2D imaging as possible to define the cardiac anatomy before turning on color flow Doppler. Excessive use of color flow Doppler is a common occurrence, particularly when the examiner has limited experience with TEE and/or unfamiliarity with the displayed anatomy.

Download

Copyright Disclaimer:
This site does not store any files on its server. We only index and link to content provided by other sites. Please contact the content providers to delete copyright contents if any and email us, we'll remove relevant links or contents immediately.