APPENDIX: Color Plates

Plate 33-1 "Normal" color Doppler aliasing. In this echocardiogram, "normal" color Doppler aliasing is seen because laminar flow of blood through the mitral valve and into the left ventricle exceeds the Nyquist limit (68 cm/sec in this example—see the color reference icon at the upper right of the figure), thereby resulting in reversal of the color coding of flow direction. Notice that this color reversal occurs across fairly broad, regular areas and not in a random or point-by-point fashion as occurs with turbulent flow (always abnormal). In this example, follow the blue flow from high in the left atrium as it accelerates into the mitral orifice, and notice how color Doppler depicts the increasing flow velocities: the blue color becomes lighter and lighter until the Nyquist limit is reached. Then, color reversal occurs, with light blue becoming yellow. Just at that reversal point, the velocity equals the Nyquist limit, in this example 68 cm/sec. Subsequent reversals may occur at that limit or at multiples of that limit. LA, left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle. (From Cahalan MK: Intraoperative Transesophageal Echocardiography. An Interactive Text and Atlas. New York, Churchill Livingstone, 1997.)

Plate 33-2 Color Doppler aliasing depicting turbulent flow. In this echocardiogram, color Doppler reveals aliasing caused by severe mitral regurgitation: a broad-based systolic color jet emanating from the mitral valve and extending far into the left atrium. This jet is composed of a mosaic of colors mixed in a seemingly random, point-by-point fashion because the jet results from the turbulent flow of mitral regurgitation. Turbulence is never normal in the heart, and thus mosaic jets such as the one shown here are highly valuable diagnostic signs of underlying pathology. LA, left atrium; LV, left ventricle; LVOT, left ventricular outflow tract. (From Cahalan MK: Intraoperative Transesophageal Echocardiography. An Interactive Text and Atlas. New York, Churchill Livingstone, 1997.)

Plate 33-3 Color Doppler imaging of severe mitral stenosis. This four-chamber echocardiogram reveals a thickened and narrowed mitral valve (MV) indicative of mitral stenosis (MS). Color Doppler demonstrates (1) acceleration of blood flow into the stenotic valve (a light blue semicircular area immediately above the valve called "PISA"—proximal isovelocity surface area), (2) a narrow color jet across the valve itself, and (3) a 1 by 4-cm color jet extending from the undersurface of the valve into the left ventricle. LA, left atrium; LV, left ventricle; RA, right atrium; RV, right ventricle. (From Cahalan MK: Intraoperative Transesophageal Echocardiography. An Interactive Text and Atlas. New York, Churchill Livingstone, 1997.)

Plate 33-4 Severe mitral regurgitation with a wall-hugging jet. This honed-down five-chamber echocardiogram reveals severe mitral regurgitation. The long color jet has a fairly broad base and an eccentric direction indicative of severe mitral regurgitation. Wall-hugging jets such as this one have a small cross-sectional area because much of their energy is absorbed by the wall of the atrium. The mechanism of the regurgitation is apparent: the anterior leaflet (on the left side of the video screen) is prolapsing and allowing blood to escape beneath it and jet over the surface of the posterior leaflet into the left atrium (LA). LV, left ventricle; MV, mitral valve. (From Cahalan MK: Intraoperative Transesophageal Echocardiography. An Interactive Text and Atlas. New York, Churchill Livingstone, 1997.)