| Echocardiography is the use of ultrasound to evaluate the heart and proximal great vessels. Echocardiography complements other diagnostic procedures by quantifying the dynamic events of the cardiac cycle. Cardiac chamber and wall dimensions can be determined; the anatomy and motion of valves can be visualized; and pressure gradients, blood flow volumes, and several indices of cardiac function can be calculated. Echocardiography can also identify changes in myocardial tissue texture
indicative of ischemia and fibrosis and delineate masses, valvular vegetations, pericardial effusion, and many other features previously verifiable only at necropsy. There are 3 main types of echocardiography: two-dimensional, M-mode, and Doppler. Two-dimensional echocardiography provides a wedge-shaped, two-dimensional image of the heart in real-time motion. Several standard long-axis and short-axis views obtained from standard imaging windows on the thorax have been
developed for dogs, cats, horses, and cows. M-mode echocardiography is produced by a one-dimensional beam of ultrasound that penetrates the heart, providing an “ice-pick view.” The tissue interfaces that are encountered by the beam are then plotted on a screen. This mode of evaluation is typically used to measure chamber dimensions, wall thickness, valve motion, and great vessel dimensions. Doppler echocardiography employs the principle of changing frequency
of the ultrasonic beam after it contacts a moving RBC to measure flow velocity and thus identify turbulent or high-velocity flow. This can locate cardiac murmurs. |
