Concurrent TTE images can serve as a baseline for rapid and noninvasive comparison of vegetation size, valvular insufficiency, or change in abscess cavities during the course of the patient s treatment should clinical dete- rioration occur. For tricuspid vegetations or abnormalities of the right ventricular outflow tract, visualization may be enhanced by choosing TTE rather than TEE.52 Finally, many cardiologists believe TTE is superior to TEE for quantifying hemodynamic dysfunction manifested by valvular regurgi- tation, ventricular dysfunction, and elevated left and right ventricular filling pressures and pulmonary artery pressure. These echocardiographic findings can occur in patients who have no heart failure symptoms. Both TEE and TTE may produce false-negative results if vegetations are small or have embolized.53 Even TEE may miss initial perivalvular abscesses, particularly when the study is performed early in the patient s illness.54 In such cases, the Figure. An approach to the diagnostic use of echocardiography (echo). Rx indicates prescription; TEE, transesophageal echocardiography; and TTE, transthoracic echocardiography. *For example, a patient with fever and a previously known heart murmur and no other stigmata of infective endocarditis (IE). High initial patient risks include prosthetic heart valves, many congenital heart diseases, previous endocarditis, new murmur, heart failure, or other stigmata of endocarditis. High-risk echocardiographic features include large or mobile vegetations, valvular insufficiency, suggestion of perivalvular extension, or secondary ventricular dysfunction (see text). Modified from Baddour et al.12 Copyright 2005, American Heart Association, Inc. Baddour et al Infective Endocarditis in Adults 1441 incipient abscess may be seen only as nonspecific perivalvu- lar thickening, which on repeat imaging across several days may become more recognizable as it expands and develops a cavity. Similarly, perivalvular fistulas and pseudoaneurysms develop over time, and negative early TEE images do not exclude the potential for their development. 