Book Text

Other Pathologies

Thousands of published reports have documented that TEE can reveal virtually any significant morphologic or functional pathology of the heart. TEE is particularly sensitive for abnormalities involving the left atrium and mitral valve, including masses, thrombi, and emboli, because of the proximity of the left atrium and mitral valve to the TEE transducer. In contrast, pathologies of the RV and LV apex are less reliably detected. TEE is exquisitely sensitive to air embolism, and as a result, even insignificant amounts of air in the circulation give rise to

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Figure 33-14 Continuous-wave Doppler evaluation of mitral stenosis. Continuous-wave Doppler measurement of blood flow velocities through a stenotic mitral valve is shown. At the top of the figure is a still-frame image of the four-chamber cross section used to position the Doppler cursor. On the bottom two thirds of the figure is the display in white of the instantaneous blood flow velocities (vertical axis) versus time (horizontal axis) occurring anywhere along that cursor. The electrocardiogram is shown for timing purposes, and the red horizontal line running through the Doppler tracing is the baseline (zero flow) for the flow velocities. Velocities displayed above the baseline are positive and represent flow toward the transducer. These velocities are due to mitral regurgitation and are so high that they exceed the scale used in this example. Velocities displayed below the baseline are negative and represent flow away from the transducer. These velocities are due to severe mitral stenosis and average about 2 m/sec, which is indicative of a gradient across the mitral valve of 16 mm Hg. Also note how slowly the flow velocity decreases after the peak of the E wave (indicated in the figure by "Slope"). The pressure half-time can be calculated from this slope and is markedly increased in the presence of severe mitral stenosis. (From Cahalan MK: Intraoperative Transesophageal Echocardiography. An Interactive Text and Atlas. New York, Churchill Livingstone, 1997.)

**TABLE 33-7** -- Simplified grading for mitral regurgitation*
	Jet Width at Origin (mm)	Jet Area (%LA_a )	Jet Depth (%LA_d )
Mild	>2	<25	<50
Moderate	3–5	25–50	50–90
Severe	>5	>50	>100
LA_a , left atrial area; LA_d , LA depth.
From Cahalan MK: Intraoperative Transesophageal Echocardiography: An Interactive Text and Atlas. New York, Churchill Livingstone, 1996.

*Systolic jet width is assessed with color Doppler in the five- or four-chamber view at the closure point of the mitral valve (the origin of the regurgitant jet). The transducer should be repositioned until the origin of the jet is clearly imaged. Failure to image the origin of the jet may lead to overestimation of its severity. Systolic jet area is assessed with color Doppler in the five- or four-chamber view. %LA_a is the percentage of the LA_a occupied by the plume of the color jet (the area of turbulent flow depicted by the mosaic of color pixels). This parameter is markedly affected by left ventricular systolic pressure. Failure to adjust color or two-dimensional gains correctly may lead to underestimation or overestimation of the severity of the regurgitation. Color gain should be set just below the level that results in random color sparkle, and two-dimensional gains should be set at the minimum levels allowing adequate visualization of cardiac structures. Systolic jet depth is assessed with color Doppler in the five- or four-chamber view. %LA_d is the depth of penetration of the jet into the left atrium expressed as a percentage of the distance from the mitral annulus to the posterior wall of the left atrium. This parameter is also markedly affected by left ventricular systolic pressure. In severe mitral regurgitation, the regurgitant jet may extend into one or more pulmonary veins and may cause transient reversal of pulmonary venous blood flow.

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Figure 33-15 Pulmonary vein flow reversal and severe mitral regurgitation. Pulsed-wave Doppler measurement of blood flow velocities in the left upper pulmonary vein (LUPV) is shown. At the top of the figure is a still-frame image of the two-dimensional cross section used to position the Doppler sampling volume (the white circle). On the bottom two thirds of the figure is the display of the instantaneous blood flow velocities (vertical axis) versus time (horizontal axis) occurring in the left upper pulmonary vein. The electrocardiogram is shown for timing purposes, and the gray horizontal line running through the Doppler tracing is the baseline (zero flow) for the flow velocities. Velocities displayed above the baseline are positive and represent flow toward the transducer (in this case, into the left atrium). Velocities displayed below the baseline are negative and represent flow away from the transducer (in this case, into the left upper pulmonary vein). This Doppler tracing documents systolic flow reversal (normally it is positive, that is, toward the left atrium [LA] in systole) and confirms the presence of severe mitral regurgitation. (From Cahalan MK: Intraoperative Transesophageal Echocardiography. An Interactive Text and Atlas. New York, Churchill Livingstone, 1997.)

impressive densities on the video display. Currently, accurate estimation of the amount of air in the circulation is impossible with TEE. However, large amounts typically opacify the involved chambers until they form collections (very bright densities) in the most superiorly positioned parts of the chambers (i.e., the anterior endocardial surface of the left ventricle in a supine patient). Pulmonary emboli may be seen with TEE if they lodge proximal to the bifurcation of the main pulmonary artery. TEE is an exceedingly valuable tool for the evaluation of congenital heart defects. The reader is directed to an excellent review article on this topic by Miller-Hance and Silverman.^[93]