The standard echocardiographic exam in small animals

The echocardiographic examination usually starts with the two-dimensional technique (B-mode), also called real time echocardiography. The two-dimensional technique allows the evaluation of anatomy and spatial relationship of cardiac structures. Monodimensional (M-mode) and Doppler echocardiography represent other imaging modalities overlapped and guided by two-dimensional imaging. For the echocardiographic exam it is necessary use specific transducers, called phased-array. These probes work with a high frame rate, are adapted to the application in the intercostal space, and allows simultaneous B-mode and Doppler acquisition (duplex or triplex imaging). The standard transducer locations on the thorax, called windows, are three and allow to obtain standard imaging planes for two-dimensional echocardiography. Imaging planes obtained from each transducer location are indicated as views and are named with respect to their orientation with the left ventricle or ascending aorta. A long-axis plane is a plane that is longitudinal to the long axis of the heart from apex to base. A short-axis plane is a plane that is perpendicular to the long-axis of the heart. Each view is further identified by the number of cardiac chambers imaged. M-mode ehocardiography uses a narrow ultrasound beam to image only a small portion of the heart and detect only the axial motion of cardiac structures. M-mode technique is guided by B-mode and individual cardiac structures are imaged by moving a single ultrasound beam from apex to base of the heart. The M-mode does not reproduce the heart anatomy and cardiac structure are identified by their characteritic motion pattern. Doppler echocardiography allows to study cardiac blood flows and define flow velocity, direction and quality (laminar or turbolent flow). Doppler imaging is particularly valuable in the diagnosis of acquired valvular heart diseases and congenital heart diseases, in which abnormal flow jets are present. Doppler echocardiography includes three different modalities: 1) pulsed-wave (PW); 2) continuous-wave (CW); 3) color-flow mapping (CFM).