Apical 4-chamber view of an echocardiogram without and with contrast-enhanced imaging of the left ventricle

The four-chamber view is initially obtained by imaging at the fundamental (interrogating) frequency (panel A). The same image after administration of an echocardiographic contrast agent (panel B). Note that the endocardium is continuously seen. Harmonic imaging at 7 MHz following echocardiographic contrast administration demonstrates considerable improvement in the contrast effect; both the cavity outline and that of the myocardium are identified with greater confidence.