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Cardiovascular Imaging A handbook for clinical practice - Part 4

Transesophageal siêu âm tim (TEE) vượt qua rất nhiều những hạn chế này và đã được chứng minh trong nhiều nghiên cứu hơn nhiều so với TTE cho việc xác định các vegetations (Bảng 7.1). Độ phân giải cao của TEE, khả năng phi cơ có nhiều lớp cánh | Echocardiography in infective endocarditis 79 Table 7.1 Comparative value of transthoracic echocardiography TTE and transesophageal echocardiography TEE in the diagnosis of valvular vegetations. Reference n Prostheses Transthoracic echo Transesophageal echo Sensitivity Specificity Sensitivity Specificity Mugge etal. 1989 4 91 24 58 90 Shively etal. 1991 5 66 18 44 94 98 100 Daniel etal. 1993 6 33 100 36 82 Shapiro etal. 1994 7 68 68 91 87 91 Figure 7.4 Transesophageal echocardiography demonstrating large mitral vegetation. LA left atrium LV left ventricle. Transesophageal echocardiography TEE overcomes many of these limitations and has been shown in many studies to be far superior to TTE for the identification of vegetations Table 7.1 . The higher resolution of TEE multiplane capabilities and proximity to the valves explain the better sensitivity of TEE in detecting vegetations compared with TTE in both native valve IE 90-100 and prosthetic valve IE 86-94 .1 3 8 TEE allows a complete assessment of vegetation characteristics such as location size and number of vegetations Fig. 7.4 . TEE is also superior to TTE in the detection of pacemaker lead vegetations.1 A negative TEE examination has a very high negative predictive value for IE in patients with native heart valve over 90 .3 The rare false-negative results may be related to an incomplete TEE examination TEE performed very early in 80 Chapter 7 the infectious process before the development of vegetations or vegetations that are too small to be detected or have already embolized. Careful multiplane TEE examination might reduce the likelihood of false-negative results. In patients with prosthetic valves false-negative results are more prone to occur possibly because of incomplete visualization presence of artifacts and interference. In these patients a negative TEE does not completely exclude the diagnosis of IE. Although TEE specificity for IE vegetations is high 88-100 possible falsepositive findings may occur in