Case Studies In Small Animal
Color Flow Doppler
This frame was acquired in systole. It shows blood flow starting as laminar flow away from the transducer (blue) in the left ventricle (LV) that aliases (turns gold) just before it reaches the mitral valve. As it crosses the mitral valve, the Doppler pattern turn into a mosaic of colors characteristic of a high velocity jet. This jet projects back into the left atrium. The jet is eccentric, striking the left lateral wall of the left atrium (LA) and then hugging the wall as it wraps around within the left atrial chamber. RV; right ventricle, RA; right atrium.
A color flow Doppler image also taken in systole but taken from a left apical four-chamber view. Several characteristics of the flow can be appreciated from this view. Flow again is first laminar in the left ventricle (LV) as it flows away from the transducer as a solid blue mass. As it starts to approach the mitral valve, it turns a lighter shade of blue as the velocity approaches the Nyquist limit (0.43 meters/second in this case) shown on the color bar to the left. It then exceeds 0.43 meters/second and wraps around (i.e., aliases) to become a gold color and then a deep red color. It then briefly turns blue again and then gold as flow continues to accelerate toward the orifice in the mitral valve. The flow pattern narrows as it goes through the mitral valve to form the base of the jet. However, this narrowed region is quite wide in comparison to dogs with lesser disease and corresponds to the large defect seen in the mitral valve on the two-dimensional echocardiograms. The jet is large, filling the entire left atrium. RV; right ventricle.
This right parasternal cross-sectional view of the mitral valve region shows the base of the color flow jet as it crosses through the mitral valve defect (below the left ventricular outflow tract [LVOT] in this picture). It appears to be very large. However, it is difficult to place the ultrasound beam exactly at the origin of the jet so this large base could be slightly inside the left atrium and so be falsely large. RV; right ventricle.
Video clip of a color flow Doppler echocardiogram from another dog with the same abnormality as "Bingo"
Note the color flow jet that wraps around within the left atrium, first hugging the lateral wall of the left atrium and then coursing along the top of the left atrium. Pause or stop the Windows Media Player and move the "slider" slowly to the right to see the motion of the jet in slow motion.
©Mark D. Kittleson, D.V.M., Ph.D. All rights reserved.