Doppler M-mode parasternal long axis

In panel A, a diagrammatic representation of the long axis of the heart is seen on top; the transducer (T) sits on the anterior chest wall in the precordial parasternal window and the beam is swept from apex to base. The appearance of the echocardiogram at 3 beam positions on the diagram is designated by the arrows connecting the diagram to the echocardiogram which displays the cardiac structures that are imaged by the beam (bottom panel). A pericardial effusion (PE) is seen as an echo-free space posterior to the left ventricle. This space diminishes and finally disappears as the base of the heart is approached because the pericardium reflects at mid atrium.